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Camera Expsosure - mostly @ Jeff but feel free to chime in

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roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
roadtrpr said:
roadtrpr said:
roadtrpr said:
roadtrpr said:
roadtrpr said:
Putting aside if most rendition of ET is pretty bad, isn't ET trying to describe the process of controlling the light i.e. the camera exposure?

What do you think?

If you don't care to discuss, don't feel obliged. No hard feelings.

However, be warned. Even though I really do not mean to, I frustrate golly to no end ( I thought I was having a pretty exciting (even scintillating) chat when we got into some German, for example ;-) , he didn't see it that way ) whenever he tries to engage me.

Be warned2: this conversation may lead to Read Amplifier Gain/PGA and what is "camera sensitivity" ;-)

BTW, I personally do not see much value in triangle graphics or list of f-stops and SS. This is not like a trig table. Nor it is level of nomograph.
Click to expand...
Consider a scene that is "properly exposed" at f/5.6 1/200 ISO 400. Change the ISO to any other ISO setting -- the exposure will be identical (but the signal will be processed differently on the basis of the ISO setting).
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You are right in manual mode.

The context of ET is how a camera controls exposure and/or how PAS mode controls the exposure. Increase ISO, AE will reduce the exposure while maintain the brightness. That's what ET describes.
roadtrpr said:
So, the exposure is the light per area falling on the sensor and the ISO setting is a form of pre-processing to the photo. Simple, really.
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It's even simpler if the context is agreed first.
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--
Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca
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--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
 
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tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
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I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.

"total quantity" is the duration of the exposure and "light energy" is the intensity of the light (density, if you will). I like this definition as it does not define it per area ;-)
tony field said:
I just looked at a "book description" ... it indicates that it is about photography technique and also the science behind the generation of images. Hopefully, it is quite accurate overall. ... but I don't think I will invest the money to check :)
tony field said:
tony field said:
tony field said:
tony field said:
tony field said:
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gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light,
Click to expand...
True
gollywop said:
which is what the statement says.
Click to expand...
and that's not what the book said - it said "total light energy"
gollywop said:
It describes the density of light.
Click to expand...
"light energy" is a rate over time like density.
gollywop said:
So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
"total" = exposure duration; "light energy" = intensity (density) of light; and I like light energy because it get away from "per area". ;-)
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
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Great Bustard said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"??
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Yes, MBP, per area, as has been explained to you countless times before.
Great Bustard said:
lux-second is same exposure regardless of the area, no??
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Yes, just as 10 PSI (force per area) is the same pressure regardless of the area.
Great Bustard said:
Great Bustard said:
Great Bustard said:
Putting aside if most rendition of ET is pretty bad, isn't ET trying to describe the process of controlling the light i.e. the camera exposure?

What do you think?

If you don't care to discuss, don't feel obliged. No hard feelings.

However, be warned. Even though I really do not mean to, I frustrate golly to no end ( I thought I was having a pretty exciting (even scintillating) chat when we got into some German, for example ;-) , he didn't see it that way ) whenever he tries to engage me.

Be warned2: this conversation may lead to Read Amplifier Gain/PGA and what is "camera sensitivity" ;-)

BTW, I personally do not see much value in triangle graphics or list of f-stops and SS. This is not like a trig table. Nor it is level of nomograph.
Click to expand...
Consider a scene that is "properly exposed" at f/5.6 1/200 ISO 400. Change the ISO to any other ISO setting -- the exposure will be identical (but the signal will be processed differently on the basis of the ISO setting).
Click to expand...
You are right in manual mode.
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What I said is correct in any mode -- exposure is the amount of light per area falling on the sensor, and is a function *solely* of the scene luminance, relative aperture, lens transmission, and exposure time. The ISO setting affects exposure *only* inasmuch as changing the ISO results in the camera changing a parameter that does change the exposure (i.e., aperture, exposure time, and/or flash power).
Great Bustard said:
The context of ET is how a camera controls exposure and/or how PAS mode controls the exposure. Increase ISO, AE will reduce the exposure while maintain the brightness. That's what ET describes.
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The "exposure triangle" is a "brightness triangle", where brightness is all together different than, albeit related to, exposure in the same way exposure is all together different than, albeit related to, the total amount of light falling on the sensor. In short, "exposure" and "brightness" are not synonyms,
Great Bustard said:
Great Bustard said:
So, the exposure is the light per area falling on the sensor and the ISO setting is a form of pre-processing to the photo. Simple, really.
Click to expand...
It's even simpler if the context is agreed first.
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Are you going to argue, now, that, for a given scene, f/2.8 1/100 ISO 200 and f/5.6 1/100 ISO 800 have the same exposure? After all, the "exposure triangle" tells me it is so, right?
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Well, yes and no - ET is saying those are the same camera exposure settings that will result similar looking photo.
Great Bustard said:
Would be nice if it were defined as such,
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It's already defined as Hv*t.
Great Bustard said:
really -- then we could say that f/2.8 on mFT has the same exposure as f/5.6 on FF and make explaining Equivalence a little bit easier. ;-)
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You wish ;-)
 
mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.
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You are correct -- it is not vague. But it is wrong. Exposure is the amount of [visible] light per area that falls on the sensor.
mostlyboringphotog said:
"total quantity" is the duration of the exposure...
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No, the duration of the exposure is time.
mostlyboringphotog said:
...and "light energy" is the intensity of the light (density, if you will).
Click to expand...
"Light energy" is neither the intensity of the light (that would be light energy per area per time) nor the density of the light (that would be light energy per area).
mostlyboringphotog said:
I like this definition as it does not define it per area ;-)
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I would like it if a dollar bought me anything I wanted to buy, but...
 
mostlyboringphotog said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light,
Click to expand...
True
mostlyboringphotog said:
which is what the statement says.
Click to expand...
and that's not what the book said - it said "total light energy"
mostlyboringphotog said:
It describes the density of light.
Click to expand...
"light energy" is a rate over time like density.
mostlyboringphotog said:
So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
"total" = exposure duration; "light energy" = intensity (density) of light; and I like light energy because it get away from "per area". ;-)
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
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Exposure is measured in Lux-seconds, i.e., Lux*s.

A Lux is a lumen/m^2.

Luminous energy is lumen-seconds, i.e., lumen*s.

So, Exposure = Lux*s = (lumen/m^2)*s = (lumen*s)/m*2 = (Luminous-energy)/m^2.

Luminous energy is not a density of light, but luminous-energy per unit area is, and it's called exposure.

Now, you wonder why you frustrate (better yet, irritate) me no end. We've been through all this before - with me and with others - in exactly the same detail. In this way you are repeatedly shown to be wrong, yet you come back again and again trying to justify erroneous notions using this and that kind of sophistry, butchered logic, and pathetically embarrassing deliberative flailing.

I wasn't being condescending above when said "please be a good boy." I was making a polite request, which, it appears, you have chosen not to respect.

--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
 
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mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.

"total quantity" is the duration of the exposure and "light energy" is the intensity of the light (density, if you will). I like this definition as it does not define it per area ;-)
Click to expand...
I did not know that a "definition" is a matter "liking it or not". It is a matter the precision of words. In other words, you change your interpretation situationally for what ever purposes you want ... this does not lead to meaningful conversation since the parties involved have no idea about that which is "really being discussed". Sometimes you use the measurement of exposure in terms of lux-seconds, and sometimes you ignore the meaning of "lux" simply because you sometimes you might or might not "like" it for your (lack of) point. That is not a useful way for an engineer to think.

You stated above " lux-second is same exposure regardless of the area" ... do you realize or understand what you actually said? Did you really mean "lux" soap as an excellent thing to clean your hands or mouth or a photograph unit of light? Did you mean "second" as a unit of time measurement or as an ordering (as in first, second, third, fourth) ?? Based on the flexibility of your personal instantaneous meaning of words, it could be any of the ad-hoc interpretations - or even a mix.

Now, after all of the discussions over the past few months, I find this to be most disappointing. So sad.... I had greater hopes...
mostlyboringphotog said:
mostlyboringphotog said:
I just looked at a "book description" ... it indicates that it is about photography technique and also the science behind the generation of images. Hopefully, it is quite accurate overall. ... but I don't think I will invest the money to check :)
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
...
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--
Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca
 
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tony field said:
mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.

"total quantity" is the duration of the exposure and "light energy" is the intensity of the light (density, if you will). I like this definition as it does not define it per area ;-)
Click to expand...
I did not know that a "definition" is a matter "liking it or not". It is a matter the precision of words. In other words, you change your interpretation situationally for what ever purposes you want ... this does not lead to meaningful conversation since the parties involved have no idea about that which is "really being discussed". Sometimes you use the measurement of exposure in terms of lux-seconds, and sometimes you ignore the meaning of "lux" simply because you sometimes you might or might not "like" it for your (lack of) point. That is not a useful way for an engineer to think.

You stated above " lux-second is same exposure regardless of the area" ... do you realize or understand what you actually said? Did you really mean "lux" soap as an excellent thigs to clean your hands or mouth or a photograph unit of light? Did you mean "second" as a unit of time measurement or as an ordering (as in first, second, third, fourth) ?? Based on the flexibility of your personal instantaneous meaning of words, it could be any of the ad-hoc interpretations - or even a mix.

Now, after all of the discussions over the past few months, I find this to be most disappointing. So sad.... I had greater hopes...
Click to expand...
I'm sorry that I have disappointed you :-( again :-( :-( but if I need to state that "by lux I do not mean soap", well, what can I say.

All I had hoped is that to remind the quote said "light energy" and not "light" and I think there is difference.

And "cleaning mouth"? Usually that is reference to "potty mouth"; is there more to read in that for me?
tony field said:
tony field said:
tony field said:
I just looked at a "book description" ... it indicates that it is about photography technique and also the science behind the generation of images. Hopefully, it is quite accurate overall. ... but I don't think I will invest the money to check :)
tony field said:
tony field said:
tony field said:
tony field said:
tony field said:
...
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--
Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca
Click to expand...
 
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"??
Click to expand...
Yes, MBP, per area, as has been explained to you countless times before.
mostlyboringphotog said:
lux-second is same exposure regardless of the area, no??
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Yes, just as 10 PSI (force per area) is the same pressure regardless of the area.
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
Putting aside if most rendition of ET is pretty bad, isn't ET trying to describe the process of controlling the light i.e. the camera exposure?

What do you think?

If you don't care to discuss, don't feel obliged. No hard feelings.

However, be warned. Even though I really do not mean to, I frustrate golly to no end ( I thought I was having a pretty exciting (even scintillating) chat when we got into some German, for example ;-) , he didn't see it that way ) whenever he tries to engage me.

Be warned2: this conversation may lead to Read Amplifier Gain/PGA and what is "camera sensitivity" ;-)

BTW, I personally do not see much value in triangle graphics or list of f-stops and SS. This is not like a trig table. Nor it is level of nomograph.
Click to expand...
Consider a scene that is "properly exposed" at f/5.6 1/200 ISO 400. Change the ISO to any other ISO setting -- the exposure will be identical (but the signal will be processed differently on the basis of the ISO setting).
Click to expand...
You are right in manual mode.
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What I said is correct in any mode -- exposure is the amount of light per area falling on the sensor, and is a function *solely* of the scene luminance, relative aperture, lens transmission, and exposure time. The ISO setting affects exposure *only* inasmuch as changing the ISO results in the camera changing a parameter that does change the exposure (i.e., aperture, exposure time, and/or flash power).
mostlyboringphotog said:
The context of ET is how a camera controls exposure and/or how PAS mode controls the exposure. Increase ISO, AE will reduce the exposure while maintain the brightness. That's what ET describes.
Click to expand...
The "exposure triangle" is a "brightness triangle", where brightness is all together different than, albeit related to, exposure in the same way exposure is all together different than, albeit related to, the total amount of light falling on the sensor. In short, "exposure" and "brightness" are not synonyms,
mostlyboringphotog said:
mostlyboringphotog said:
So, the exposure is the light per area falling on the sensor and the ISO setting is a form of pre-processing to the photo. Simple, really.
Click to expand...
It's even simpler if the context is agreed first.
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Are you going to argue, now, that, for a given scene, f/2.8 1/100 ISO 200 and f/5.6 1/100 ISO 800 have the same exposure? After all, the "exposure triangle" tells me it is so, right?
Click to expand...
Well, yes and no - ET is saying those are the same camera exposure settings that will result similar looking photo.
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By "similar looking" you mean same brightness. In other words, as I said, "Brightness Triangle", not "Exposure Triangle".
mostlyboringphotog said:
mostlyboringphotog said:
Would be nice if it were defined as such,
Click to expand...
It's already defined as Hv*t.
Click to expand...
Yes -- exposure is the product of intensity (light energy per time per area) and time giving us units of light energy per area.
mostlyboringphotog said:
mostlyboringphotog said:
really -- then we could say that f/2.8 on mFT has the same exposure as f/5.6 on FF and make explaining Equivalence a little bit easier. ;-)
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You wish ;-)
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Well, if not, looks like the "exposure triangle" isn't talking about exposure at all; rather, it is talking about brightness.
 
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gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
Putting aside if most rendition of ET is pretty bad, isn't ET trying to describe the process of controlling the light i.e. the camera exposure?

What do you think?

If you don't care to discuss, don't feel obliged. No hard feelings.

However, be warned. Even though I really do not mean to, I frustrate golly to no end ( I thought I was having a pretty exciting (even scintillating) chat when we got into some German, for example ;-) , he didn't see it that way ) whenever he tries to engage me.

Be warned2: this conversation may lead to Read Amplifier Gain/PGA and what is "camera sensitivity" ;-)

BTW, I personally do not see much value in triangle graphics or list of f-stops and SS. This is not like a trig table. Nor it is level of nomograph.
Click to expand...
Consider a scene that is "properly exposed" at f/5.6 1/200 ISO 400. Change the ISO to any other ISO setting -- the exposure will be identical (but the signal will be processed differently on the basis of the ISO setting).
Click to expand...
You are right in manual mode.

The context of ET is how a camera controls exposure and/or how PAS mode controls the exposure. Increase ISO, AE will reduce the exposure while maintain the brightness. That's what ET describes.
gollywop said:
So, the exposure is the light per area falling on the sensor and the ISO setting is a form of pre-processing to the photo. Simple, really.
Click to expand...
It's even simpler if the context is agreed first.
Click to expand...
--
Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca
Click to expand...
Click to expand...
--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
Click to expand...
 
mostlyboringphotog said:
tony field said:
mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.

"total quantity" is the duration of the exposure and "light energy" is the intensity of the light (density, if you will). I like this definition as it does not define it per area ;-)
Click to expand...
I did not know that a "definition" is a matter "liking it or not". It is a matter the precision of words. In other words, you change your interpretation situationally for what ever purposes you want ... this does not lead to meaningful conversation since the parties involved have no idea about that which is "really being discussed". Sometimes you use the measurement of exposure in terms of lux-seconds, and sometimes you ignore the meaning of "lux" simply because you sometimes you might or might not "like" it for your (lack of) point. That is not a useful way for an engineer to think.

You stated above " lux-second is same exposure regardless of the area" ... do you realize or understand what you actually said? Did you really mean "lux" soap as an excellent thigs to clean your hands or mouth or a photograph unit of light? Did you mean "second" as a unit of time measurement or as an ordering (as in first, second, third, fourth) ?? Based on the flexibility of your personal instantaneous meaning of words, it could be any of the ad-hoc interpretations - or even a mix.

Now, after all of the discussions over the past few months, I find this to be most disappointing. So sad.... I had greater hopes...
Click to expand...
I'm sorry that I have disappointed you :-( again :-( :-( but if I need to state that "by lux I do not mean soap", well, what can I say.

All I had hoped is that to remind the quote said "light energy" and not "light" and I think there is difference.

And "cleaning mouth"? Usually that is reference to "potty mouth"; is there more to read in that for me?
Click to expand...
Sadly, Gollywop is exactly correct in his assessment. GB is unbelievably patient with his dialogues. I think I have to join the gollywop camp and sadly leave GB's patience in the dust.
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
I just looked at a "book description" ... it indicates that it is about photography technique and also the science behind the generation of images. Hopefully, it is quite accurate overall. ... but I don't think I will invest the money to check :)
Click to expand...
Click to expand...
Click to expand...
Click to expand...
--
Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca
 
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gollywop said:
mostlyboringphotog said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light,
Click to expand...
True
gollywop said:
which is what the statement says.
Click to expand...
and that's not what the book said - it said "total light energy"
gollywop said:
It describes the density of light.
Click to expand...
"light energy" is a rate over time like density.
gollywop said:
So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
"total" = exposure duration; "light energy" = intensity (density) of light; and I like light energy because it get away from "per area". ;-)
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
gollywop said:
...
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Exposure is measured in Lux-seconds, i.e., Lux*s.

A Lux is a lumen/m^2.

Luminous energy is lumen-seconds, i.e., lumen*s.

So, Exposure = Lux*s = (lumen/m^2)*s = (lumen*s)/m*2 = (Luminous-energy)/m^2.
Click to expand...
I get the math.
gollywop said:
Luminous energy is not a density of light, but luminous-energy per unit area is, and it's called exposure.
Click to expand...
However, respectfully, what is the illuminance 1m away from a 1 candela light source?

I think it's 1 lux; if this is wrong, this is source of my confusion.
gollywop said:
Now, you wonder why you frustrate (better yet, irritate) me no end. We've been through all this before - with me and with others - in exactly the same detail. In this way you are repeatedly shown to be wrong, yet you come back again and again trying to justify erroneous notions using this and that kind of sophistry, butchered logic, and pathetically embarrassing deliberative flailing.

I wasn't being condescending above when said "please be a good boy." I was making a polite request, which, it appears, you have chosen not to respect.
Click to expand...
I'll let others decide if "please be a good boy." is condescending or not within the DPR forum context.
gollywop said:
--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
Click to expand...
 
Great Bustard said:
mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.
Click to expand...
You are correct -- it is not vague. But it is wrong. Exposure is the amount of [visible] light per area that falls on the sensor.
Great Bustard said:
"total quantity" is the duration of the exposure...
Click to expand...
No, the duration of the exposure is time.
Click to expand...
And that time will determine the "total quantity of light energy"
Great Bustard said:
Great Bustard said:
...and "light energy" is the intensity of the light (density, if you will).
Click to expand...
"Light energy" is neither the intensity of the light (that would be light energy per area per time) nor the density of the light (that would be light energy per area).
Click to expand...
More light energy, more intense light; higher density more light energy - I say this to show my way thinking. Not to claim I am right.
Great Bustard said:
Great Bustard said:
I like this definition as it does not define it per area ;-)
Click to expand...
I would like it if a dollar bought me anything I wanted to buy, but...
Click to expand...
I'll know my source of error if the illuminance 1m away from a 1 candela light source is not 1 lux. I asked the same question to golly.
 
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
tony field said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
I take your word for that. What MBP presented is, in that case, a misrepresentation of the book. I do not have a copy. It is frustrating to base a discussion on an out-of-context set of words. We can only comment on "words we are presented with".
Click to expand...
I could not quote the whole book but " total quantity of light energy " is correct even out of context; and I think it's a carefully stated technical definition. I see the difference between "total quantity of light" and "total quantity of light energy". I don't think it's a vague description.
Click to expand...
You are correct -- it is not vague. But it is wrong. Exposure is the amount of [visible] light per area that falls on the sensor.
mostlyboringphotog said:
"total quantity" is the duration of the exposure...
Click to expand...
No, the duration of the exposure is time.
Click to expand...
And that time will determine the "total quantity of light energy"
Click to expand...
Time is a component, just as intensity and area are components.
mostlyboringphotog said:
mostlyboringphotog said:
mostlyboringphotog said:
...and "light energy" is the intensity of the light (density, if you will).
Click to expand...
"Light energy" is neither the intensity of the light (that would be light energy per area per time) nor the density of the light (that would be light energy per area).
Click to expand...
More light energy, more intense light;
Click to expand...
Not necessarily. You can get more light energy from longer times and/or larger areas.
mostlyboringphotog said:
higher density more light energy - I say this to show my way thinking. Not to claim I am right.
mostlyboringphotog said:
mostlyboringphotog said:
I like this definition as it does not define it per area ;-)
Click to expand...
I would like it if a dollar bought me anything I wanted to buy, but...
Click to expand...
I'll know my source of error if the illuminance 1m away from a 1 candela light source is not 1 lux. I asked the same question to golly.
Click to expand...
Gollywop answered correctly.
 
roadtrpr said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
Click to expand...
If I misinterpreted the intent of your post, please excuse me. It appeared to me to be nothing other than a justification for the unjustifiable. But I will agree that appearances can be deceiving, and, in this case, I'll accept that they were. :-)
 
gollywop said:
roadtrpr said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
Click to expand...
If I misinterpreted the intent of your post, please excuse me. It appeared to me to be nothing other than a justification for the unjustifiable. But I will agree that appearances can be deceiving, and, in this case, I'll accept that they were. :-)
Click to expand...
Fair Enough. In return I will say that at best I think the statement is problematic and certainly taken in its entirety at face value is not correct. I do hope though that no one judges the value of the book by one careless poorly worded casual statement.

gollywop said:
--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
Click to expand...
 
roadtrpr said:
gollywop said:
roadtrpr said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
Click to expand...
If I misinterpreted the intent of your post, please excuse me. It appeared to me to be nothing other than a justification for the unjustifiable. But I will agree that appearances can be deceiving, and, in this case, I'll accept that they were. :-)
Click to expand...
Fair Enough. In return I will say that at best I think the statement is problematic and certainly taken in its entirety at face value is not correct. I do hope though that no one judges the value of the book by one careless poorly worded casual statement.
Click to expand...
Well, just how do we know it was careless? And I think "casual" is a rather self-serving description; it didn't seem so casual to me. Meanwhile, however, it remains as an incorrect statement about one of the most fundamental elements of photographic know-how and understanding. That more than gives one pause.

--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
 
Last edited:
gollywop said:
roadtrpr said:
gollywop said:
roadtrpr said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
Click to expand...
If I misinterpreted the intent of your post, please excuse me. It appeared to me to be nothing other than a justification for the unjustifiable. But I will agree that appearances can be deceiving, and, in this case, I'll accept that they were. :-)
Click to expand...
Fair Enough. In return I will say that at best I think the statement is problematic and certainly taken in its entirety at face value is not correct. I do hope though that no one judges the value of the book by one careless poorly worded casual statement.
Click to expand...
Well, just how do we know it was careless? And I think "casual" is a rather self-serving description; it didn't seem so casual to me. Meanwhile, however, it remains as an incorrect statement about one of the most fundamental elements of photographic know-how and understanding. That more than gives one pause.
Click to expand...
Both careless and casual are my opinion. Based on the book in general do you think the statement was as deliberate and as well thought out as the writing in general?

A possibility is that instead of being careless and casual is that although the authors seem very knowledgeable in general they simply don't have a proper understanding of exposure.
gollywop said:
--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
Click to expand...
 
Last edited:
roadtrpr said:
gollywop said:
roadtrpr said:
gollywop said:
roadtrpr said:
tony field said:
mostlyboringphotog said:
Great Bustard said:
mostlyboringphotog said:
So, another maxed out exposure triangle thread...

If you care to continue the scintillating (today's word for golly ;-) ) conversation, I'd like to start from the following quote from The Manual of Photography Tenth Edition - Chapter 12

"The term exposure in photography describes the total quantity of light energy incident on a sensitive material, which in general terms is the photographic exposure. It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, which is more specifically the camera exposure." - bold added.
Click to expand...
Exposure is the amount of light per area that falls on the recording medium, not the total quantity of light.
Click to expand...
"per area"?? lux-second is same exposure regardless of the area, no??
Click to expand...
As a "definition", the book fails obviously. It makes no mention of the units of measure - you pulled that out of your magic box.

Reading the book you can easily infer that "the total quantity of light energy incident on a sensitive material on a 4x5 cm surface" is the same exposure as "the total quantity of light energy incident on a sensitive material on a 2x3 cm surface". That is what the written words "total quantity of light" (which I think is the sum of all photons presented to the surface) allows. In other words, the book has a an obviously incorrect definition of "exposure".

It's plausible vague description: "It may alternatively describe the process of controlling the light energy reaching a sensitive material in a camera, ..." is reasonable. It is certain wrong when it continues the sentence with "which is more specifically the camera exposure" ... and it does not remotely define what a "camera exposure" means.

All in all, a sloppy and error packed definition from what is supposed to be a reliable technical resource. This is as sloppy and poor as the descriptions of exposure provided in CambridgeInColour !!

Such resources should be correct, complete and well written. Seems like many writers prefer things to be pleasing and nicely written ... accuracy is secondary.
Click to expand...
Is it significant that the book said, "The term exposure in photography describes..." And did not say exposure is ...? It is a big book and exposure was thoroughly discussed well before chapter 12 and I don't know enough to judge, but I think those discussions and the rest of chapter 12 need to be read before criticizing the use of the word exposure in the book. I do not see the statement in question as being a definition of exposure at all. So far as units of measure and what was meant by "camera exposure" those were covered in chapters prior to chapter 12.

The statement was taken out of a huge amount of context.
Click to expand...
Describe: verb: give an account in words of (someone or something), including all the relevant characteristics, qualities, or events.

Exposure does not describe total light, which is what the statement says. It describes the density of light.

So, you've made a nice try, but it doesn't fly. The statement is incorrect, regardless of context. It provides an incorrect description of exposure. Nor should anyone who could correctly define exposure be excused for making such a description.
Click to expand...
That definition of describe is what prompted my question, so I appreciate your input. I did not say the statement was correct or incorrect, so do not get what you mean about making a nice try, but I do appreciate hearing your opinion.
Click to expand...
If I misinterpreted the intent of your post, please excuse me. It appeared to me to be nothing other than a justification for the unjustifiable. But I will agree that appearances can be deceiving, and, in this case, I'll accept that they were. :-)
Click to expand...
Fair Enough. In return I will say that at best I think the statement is problematic and certainly taken in its entirety at face value is not correct. I do hope though that no one judges the value of the book by one careless poorly worded casual statement.
Click to expand...
I don't think there is much concern about judging the book. The first edition was printed in 1890 (not a typo) and surely someone would have pointed out how wrong they are by now ;-)
roadtrpr said:
roadtrpr said:
--
gollywop
http://g4.img-dpreview.com/D8A95C7DB3724EC094214B212FB1F2AF.jpg
Click to expand...
Click to expand...
 
mostlyboringphotog said:
gollywop said:
Exposure is measured in Lux-seconds, i.e., Lux*s.

A Lux is a lumen/m^2.

Luminous energy is lumen-seconds, i.e., lumen*s.

So, Exposure = Lux*s = (lumen/m^2)*s = (lumen*s)/m*2 = (Luminous-energy)/m^2.
Click to expand...
I get the math.
Click to expand...
Do you get the concept, though? Specifically, do you understand that exposure is defined as the luminous energy per area that falls on the sensor?
mostlyboringphotog said:
mostlyboringphotog said:
Luminous energy is not a density of light, but luminous-energy per unit area is, and it's called exposure.
Click to expand...
However, respectfully, what is the illuminance 1m away from a 1 candela light source?

I think it's 1 lux; if this is wrong, this is source of my confusion.
Click to expand...
A source with a luminous intensity of 1 candela will result in an illuminance of 1 lux at a distance of 1 meter and is subject to the inverse square relationship for other distances.
 
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