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The issue is that the ISO setting is a HINT to the camera on how to set the exposure and/or aperture and/or amplification to 1) capture an image with the appropriate exposure for the requested amplification. If ISO is set manually, you're telling the camera what amplification to use. Proper exposure may be a different exposure for different ISO settings because you're requesting the exposure to be amplified by whatever technique the camera uses. A higher ISO causes the camera to use a lower exposure for the same image lightness in the processed file.

--
Victor Engel
 
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Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
As you said, in A or S mode you can of course use the Exposure dial to adjust the exposure manually.
Click to expand...
The Wikipedia link has been posed twice in this thread. Have you read the article?
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Yes and also this one https://photographylife.com/what-is-exposure#i
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And which do you think is more authoritative?
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Both make the same point that there are only two camera settings that affect the actual “luminous exposure” of an image. However the point I'm making - and maybe it's just the definition of 'exposure' - is represented by this quote:

"For every scene, a wide range of shutter speed, aperture, and ISO settings will result in a photo of the proper brightness. Getting the proper exposure for a photo is about balancing those three settings so the rest of the photo looks good, from depth of field to sharpness."
Click to expand...
That sentence is correct. The way you have been using the term "exposure" is not:
Click to expand...
I believe that my use of the term 'exposure' is consistent with the wording above, i.e. "Getting the proper exposure for a photo is about balancing those three settings..."
Michael Jardine said:
Michael Jardine said:
Not adjusting the ISO has affected my exposure. I could have adjusted the ISO, the Aperture, or the Shutter speed in order to achieve the same even exposure that I had with the Kodachrome roll.
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Not adjusting the ISO have left your exposure unchanged, which is not what you wanted.
Click to expand...
Thus resulting in an improper exposure, per the definition above.
Michael Jardine said:
Michael Jardine said:
For example if you have ISO set to automatic, then it will automatically adjust as you change both the shutter speed and the aperture, in order to maintain the same exposure.
Click to expand...
No, it will adjust to maintain similar brightness. You set the exposure when you set the shutter speed and the f-stop, for any give scene.
Click to expand...
What I'm seeing is still "Getting the proper exposure for a photo is about balancing those three settings..."
Michael Jardine said:
Michael Jardine said:
I believe ISO indirectly affects exposure
Click to expand...
This usage could be correct.
Michael Jardine said:
particularly in digital cameras and I can see that because in A or S mode, as I adjust the ISO, the shutter speed and/or aperture will automatically adjust in order to keep the exposure settings the same.
Click to expand...
This usage is incorrect.
Click to expand...
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
Michael Jardine said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.

--
https://blog.kasson.com
 
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Still wondering what is happening in 2) and 3) of my questions - particularly, what is happening to my A1 above ISO 18000? The chart says 'values outside the normal analog range' - does that mean there is no reason to adjust the ISO above 18000?
 
JimKasson said:
JimKasson said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
JimKasson said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
 
Michael Jardine said:
Still wondering what is happening in 2) and 3) of my questions - particularly, what is happening to my A1 above ISO 18000? The chart says 'values outside the normal analog range' - does that mean there is no reason to adjust the ISO above 18000?
Click to expand...
I haven't tested the a1, but other Sony cameras, when they get way up in ISO, stop using analog gain and just boost the digital values with arithmetic. If you're shooting raw, you can do that better in post, so there's no reason to use those ISOs except to make the finder brighter.
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
Michael Jardine said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
 
Michael Jardine said:
Just saw references to this in another post. I'm trying to understand the differences between my old Nikon D800 and my new Sony A1.

What is the purpose of measuring the relationship between photo dynamic range and iso? In layman's terms I think this means that the higher the ISO, the less 'room for error' or the lesser the ability of the sensor to distinguish between ranges of light and dark, this increasing the requirement for light sources to be even and level?

1. Why do the graphs jump upwards at ISO 100? Does that mean, anything below ISO 100 is 'not real'? I guess I don't understand what 'outside the normal analog range' means.

2. What is happening to my old D800 above ISO 3200? Does that mean, the limit of the sensor is at ISO 3200? What happens above that?

3. Likewise, what is happening on my A1 sensor above ISO 20000?

Thanks in advance!

9cde9cc700224205be1cf19a9ad7f1b1.jpg.png
Click to expand...
The legenda of symbols used are just above the graph
 
JimKasson said:
Michael Jardine said:
JimKasson said:
JimKasson said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
JimKasson said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
Click to expand...
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.

--
Michael
www.Qamera.com
IG my.qamera
 
Last edited:
JimKasson said:
Michael Jardine said:
Still wondering what is happening in 2) and 3) of my questions - particularly, what is happening to my A1 above ISO 18000? The chart says 'values outside the normal analog range' - does that mean there is no reason to adjust the ISO above 18000?
Click to expand...
I haven't tested the a1, but other Sony cameras, when they get way up in ISO, stop using analog gain and just boost the digital values with arithmetic. If you're shooting raw, you can do that better in post, so there's no reason to use those ISOs except to make the finder brighter.
Click to expand...
Typically I shoot JPG for sports and typically for night sports I am at or above 12800; upon occasion as high as 20000 - with minimum shutter speed 1/1000 and aperture set manually to f/2.8.

Are you suggesting that - based on the chart - at ISO 16000 and above, I should switch from JPG to RAW? I had done this in the past but could not really tell if there was a big difference. Either way there's too much noise above 6400 so I have to fix that in post. even with JPG and in-camera NR.
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
Michael Jardine said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
Click to expand...
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.
Click to expand...
The camera may have different metering modes, which would result in different exposures depending on how the brightness varies over the scene.
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
Michael Jardine said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
Click to expand...
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.
Click to expand...
The decision as to what is a proper exposure is subjective. Light metering systems turn those subjective decisions into algorithms. There are many ways to do that. There is a saying among surgeons that if there are many ways to do a procedure, that means none of them are very good.

Can we agree on the following:

If we have two images of the same thing both with proper exposure (whatever that means) they may or may not have the same exposure.
 
robert1955 said:
Michael Jardine said:
Just saw references to this in another post. I'm trying to understand the differences between my old Nikon D800 and my new Sony A1.

What is the purpose of measuring the relationship between photo dynamic range and iso? In layman's terms I think this means that the higher the ISO, the less 'room for error' or the lesser the ability of the sensor to distinguish between ranges of light and dark, this increasing the requirement for light sources to be even and level?

1. Why do the graphs jump upwards at ISO 100? Does that mean, anything below ISO 100 is 'not real'? I guess I don't understand what 'outside the normal analog range' means.

2. What is happening to my old D800 above ISO 3200? Does that mean, the limit of the sensor is at ISO 3200? What happens above that?

3. Likewise, what is happening on my A1 sensor above ISO 20000?

Thanks in advance!

9cde9cc700224205be1cf19a9ad7f1b1.jpg.png
Click to expand...
The legenda of symbols used are just above the graph
Click to expand...
Yes I saw that. And my question still remains, what does 'values outside the normal analog range' mean? I think Jim answered but am still not clear what to do with this information.

--
Michael
www.Qamera.com
IG my.qamera
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Still wondering what is happening in 2) and 3) of my questions - particularly, what is happening to my A1 above ISO 18000? The chart says 'values outside the normal analog range' - does that mean there is no reason to adjust the ISO above 18000?
Click to expand...
I haven't tested the a1, but other Sony cameras, when they get way up in ISO, stop using analog gain and just boost the digital values with arithmetic. If you're shooting raw, you can do that better in post, so there's no reason to use those ISOs except to make the finder brighter.
Click to expand...
Typically I shoot JPG for sports and typically for night sports I am at or above 12800; upon occasion as high as 20000 - with minimum shutter speed 1/1000 and aperture set manually to f/2.8.

Are you suggesting that - based on the chart - at ISO 16000 and above, I should switch from JPG to RAW?
Click to expand...
No, I'm giving you advice for when you're shooting RAW.
Michael Jardine said:
I had done this in the past but could not really tell if there was a big difference. Either way there's too much noise above 6400 so I have to fix that in post. even with JPG and in-camera NR.
Click to expand...
 
Michael Jardine said:
Yes I saw that. And my question still remains, what does 'values outside the normal analog range' mean? I think Jim answered but am still not clear what to do with this information.
Click to expand...
Savor it.
 
Victor Engel said:
Victor Engel said:
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.
Click to expand...
The camera may have different metering modes, which would result in different exposures depending on how the brightness varies over the scene.
Click to expand...
Sure. I could also trip and fall, or the battery could die. But for the sake of this discussion, let's assume that the metering modes are delivering the same information to the sensor regardless of which of the three variables I am holding constant.

--
Michael
www.Qamera.com
IG my.qamera
 
Last edited:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
JimKasson said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
JimKasson said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
Click to expand...
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.
Click to expand...
The decision as to what is a proper exposure is subjective.

Light metering systems turn those subjective decisions into algorithms. There are many ways to do that.
Click to expand...
agree
JimKasson said:
There is a saying among surgeons that if there are many ways to do a procedure, that means none of them are very good.

Can we agree on the following:

If we have two images of the same thing both with proper exposure (whatever that means) they may or may not have the same exposure.
Click to expand...
what i'm saying is that shutter speed, aperture, and ISO all work together to generate a set of numbers for algorithms to achieve the same results given the light metering at that exact moment in time.

When I change any one of those three (it does not matter which one), the algorithms will adjust the other two in order to deliver an exposure that 'looks the same' as it did just before I changed that one. I can then make those 'not look the same' by adjusting the exposure compensation dial.

--
Michael
www.Qamera.com
IG my.qamera
 
Last edited:
JimKasson said:
JimKasson said:
Typically I shoot JPG for sports and typically for night sports I am at or above 12800; upon occasion as high as 20000 - with minimum shutter speed 1/1000 and aperture set manually to f/2.8.

Are you suggesting that - based on the chart - at ISO 16000 and above, I should switch from JPG to RAW?
Click to expand...
No, I'm giving you advice for when you're shooting RAW.
Click to expand...
So there is no reason to switch to RAW as the ISO climbs
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Not sure about the usage but that is my observation with my camera. I can lock (set) the ISO, in which case only the aperture and shutter speed may adjust to achieve the proper exposure.
Click to expand...
Proper exposure is subjective, and it it not at all the same thing as same exposure.
Michael Jardine said:
In this case, adjusting one manually (for example, aperture) will cause the other to change accordingly. However if I allow the ISO to float, then it too will change based upon the combinations of aperture and shutter speed that I choose. Maybe that is not 'exposure' but it is 'proper exposure' as used above.
Click to expand...
See above.
Click to expand...
I would guess that if I apply the same degree of subjectivity towards getting proper exposure, that will be very much the same thing as getting the same exposure.
Click to expand...
The sameness of two exposures is not subjective at all.
Click to expand...
The numbers applied to ISO (and to aperture, and to shutter speed) are objective. I don't know what the specific relationship is, but if I set any one of the three, and manually adjust one of the other two, I will always see the third adjust automatically in order to achieve the same exposure (or 'amount of light') as determined by the camera. I can then adjust that exposure subjectively using the exposure compensation dial.
Click to expand...
The decision as to what is a proper exposure is subjective.

Light metering systems turn those subjective decisions into algorithms. There are many ways to do that.
Click to expand...
agree
Michael Jardine said:
There is a saying among surgeons that if there are many ways to do a procedure, that means none of them are very good.

Can we agree on the following:

If we have two images of the same thing both with proper exposure (whatever that means) they may or may not have the same exposure.
Click to expand...
what i'm saying is that shutter speed, aperture, and ISO all work together to generate a set of numbers for algorithms to achieve the same results given the light metering at that exact moment in time.
Click to expand...
Well, not quite the same results, but I can pretty much agree with that. In some modes, when you change the ISO, the camera will change the exposure to compensate.
Michael Jardine said:
When I change one of those three, the algorithms will adjust the other two in order to deliver an exposure that 'looks the same' as just before I changed that one. I can then make those 'not look the same' by adjusting the exposure compensation dial.
Click to expand...
Again, from 50,000 feet, that's true. That's not the same as saying you get the same exposure when you change ISO.
 
Michael Jardine said:
JimKasson said:
Michael Jardine said:
Typically I shoot JPG for sports and typically for night sports I am at or above 12800; upon occasion as high as 20000 - with minimum shutter speed 1/1000 and aperture set manually to f/2.8.

Are you suggesting that - based on the chart - at ISO 16000 and above, I should switch from JPG to RAW?
Click to expand...
No, I'm giving you advice for when you're shooting RAW.
Click to expand...
So there is no reason to switch to RAW as the ISO climbs
Click to expand...
Not if you're happy with the limitations of JPEG at lower ISO.
 
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