A reminder for some memebers as to what the F stop is all about.

Started Jan 26, 2014 | Discussions
Lab D Veteran Member • Posts: 6,938
Re: Think of a fat lady and thin supermodel on the beach

Bmoon wrote:

Lab D wrote:

A fat lady and a thin supermodel are laying on the beach. Who will get sun burnt faster? Answer: both will burn/tan the same despite the fat lady having 4x the skin area.

Maybe they need a good UV filter.

Anyway, Four Thirds is the hot supermodel.

But the million dollar question is which one requires more sunscreen to reduce their exposure to the sun ?

Or which costs more, a set of 58mm filters or a set of 72mm filters? 

 Lab D's gear list:Lab D's gear list
Panasonic FZ1000 Nikon D600 Panasonic Lumix DMC-GH4
Great Bustard Forum Pro • Posts: 43,430
Re: A simple Yes or No.

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes.  Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

and display the photos at the same size.  Assuming the sensors are roughly the same efficiency, in what way will the photos be similar and in what way will they be different?

bobn2
bobn2 Forum Pro • Posts: 62,700
Re: Both sides are sort of right

Dougbm_2 wrote:

Do you guys actually get out and take photos?

How about you?

-- hide signature --

Bob

Great Bustard Forum Pro • Posts: 43,430
Re: Um...

DonSC wrote:

Great Bustard wrote:The total light is the total amount of light that falls on the portion of the sensor used to for the photo during the exposure: Total Light = Exposure · Effective Sensor Area. The same total amount of light will fall on the sensor for equivalent photos but, for different formats, this will necessarily result in a different exposure on each format, since the same total light distributed over sensors with different areas will result in a lower density of light on the larger sensor.

I've always wondered if this were really true.

It is.

For sure it's true if you mount the SAME lens on cameras with different sized sensors. But what if the lens creates a smaller image circle? A lens isn't a tube. A 300mm f/2.8 lens doesn't have to create a FF image circle. It can create a larger image circle or a smaller one.

Yes.

A 300mm f/2.8 m43 lens which creates an image circle with half the diameter of a 300mm f/2.8 FF lens will deliver the same amount of total light to the sensor.

No.  A 300 / 2.8 will put the same density of light (same light per area) on the sensor regardless of the format, but not the same total amount of light.

While the area will be smaller the density of light will be higher.

No.  The same f-ratio results in the same density, regardless of format, but not the same total amount of light on the sensor.

Isn't this what the speed boosters do?

Speedboosters (focal reducers) compress the larger image circle into a smaller image circle, and thus put the same total amount of light on the sensor.  For example, a 0.5x FR will result in half the focal length, but the aperture (entrance pupil) diameter remains the same, so the relative aperture (f-ratio) is halved since the focal length is halved.

bobn2
bobn2 Forum Pro • Posts: 62,700
Re: Um...

Great Bustard wrote:

A 300mm f/2.8 m43 lens which creates an image circle with half the diameter of a 300mm f/2.8 FF lens will deliver the same amount of total light to the sensor.

No. A 300 / 2.8 will put the same density of light (same light per area) on the sensor regardless of the format, but not the same total amount of light.

And also, the image circle isn't very tightly coupled to the format in use. I would guess that if you removed the baffles, most SHG lenses would produce pretty much a FF image circle. It's one of the things that is done to give 'edge to edge' sharpness, make the image circle large and just use the centre of it. Long FL lenses in particular tend to have big image circles.

While the area will be smaller the density of light will be higher.

No. The same f-ratio results in the same density, regardless of format, but not the same total amount of light on the sensor.

Isn't this what the speed boosters do?

Speedboosters (focal reducers) compress the larger image circle into a smaller image circle, and thus put the same total amount of light on the sensor. For example, a 0.5x FR will result in half the focal length, but the aperture (entrance pupil) diameter remains the same, so the relative aperture (f-ratio) is halved since the focal length is halved.

They reduce the whole image, and the image circle as a result. Their operation without vignetting depends on a large enough image circle.

-- hide signature --

Bob

Great Bustard Forum Pro • Posts: 43,430
Re: Question:
1

philosomatographer wrote:

Great Bustard wrote:

philosomatographer wrote:

Have you used a wide-enough range of lenses and systems to really tell, though? If so, let's just agree to disagree.

Truth be told, I don't think the IQ differential really matters to the vast majority. Post a nice pic with stripped EXIF from the 50-200 / 2.8-3.5 and say it was from the 35-100 / 2, and no one will doubt you. Post a bad pic from the 35-100 / 2, and people will praise you just because you own something so expensive. It's the same in all the forums.

Well, there we go - agreeing again.

I've any number of bad habits.

Technical quality is almost completely orthogonal to artistic merit, and it usually just doesn't matter. Pity it gets everytbody knickers in a knot when one dares talk about technicalities though!

Agreed.

The E-5 is most certainly not even 'competitive' - the sensor is horribly outdated, and these lenses are starved of a worthy sensor.

Will they not work on the EM1?

Oh yes - they work fine. Problem is, an EM1 sensor is no match for a good full-frame sensor...

I would argue otherwise, but...

...and the SHG lenses at f/2.0 hopelessly out-resolve the 16MP sensor to the point of creating moíre aliasing across the frame.

Lenses do not outresolve sensors, nor do sensors outresolve lenses. The aliasing comes from the lack of an AA filter.

The EM1 is a small step-up in image quality from the E-5.

Sure -- same lenses, same pixel count, just a bit more efficient.

From a detail rendition aspect, it's just about the best 12MP sensor you're going to ever find.But it's a noisy, DR-limited 12MP.

To me, you can't get a photo with just a lens or just a sensor. You kind of need both. So what matters is how the lens performs on the available sensors. I mean, would you brag about owning a Ferrari if it sported wheels and tires from a Camry? I mean, why not just get a Camry -- it's a pretty decent car.

The same situation applies to your high-resolution full-frame DSLR cameras and the so-so lenses you have to put on them.

The lenses I have put on my camera are not so-so. Of course, I can always want for more.

Seems we just can't win whichever way we go!

In terms of the visual properties of the photo, it's the system that matters, not the individual components. In terms of getting the photo at all, it's the operation of the equipment.  In terms of the "success" of the photo, it's the photographer's abilities, in terms of vision, competence, and processing skills that matter, not the equipment.

Dimitri_P Regular Member • Posts: 201
Re: A simple Yes or No.

Great Bustard wrote among other things:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

and display the photos at the same size. Assuming the sensors are roughly the same efficiency, in what way will the photos be similar and in what way will they be different?

The one shot with the slow lens on FF will have more noise than the one shot with the faster lens and the 4/3  shot will have more noise than the FF shot at ISO 400.

Someone over here reading this must have a FF and 4/3 camera available to take three shots and post them...

 Dimitri_P's gear list:Dimitri_P's gear list
Olympus E-1 Olympus E-500 Olympus Zuiko Digital ED 14-42mm 1:3.5-5.6 Olympus Zuiko Digital ED 40-150mm 1:4.0-5.6 Canon Pixma Pro9000 Mark II +2 more
Great Bustard Forum Pro • Posts: 43,430
Re: A simple Yes or No.

Dimitri_P wrote:

Great Bustard wrote among other things:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

and display the photos at the same size. Assuming the sensors are roughly the same efficiency, in what way will the photos be similar and in what way will they be different?

The one shot with the slow lens on FF will have more noise than the one shot with the faster lens and the 4/3 shot will have more noise than the FF shot at ISO 400.

Correct. If the sensors are equally efficient, then the first and third photos will have the same noise since the same amount of light falls on the sensors, and the middle photo will have half the noise since 4x (2 stops) more light falls on the sensor.

Someone over here reading this must have a FF and 4/3 camera available to take three shots and post them...

'Twould be nice! Of course, we need to have the shots done in RAW since the NR (noise reduction) done by the camera's jpg engine may skew the results.

CollBaxter
CollBaxter Forum Pro • Posts: 12,724
Re: A simple Yes or No.

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is.

As to the DOF we will all agree that DOF at the same F stop on different size senors are different. ( Hell I have been on this forum long enough to understand that) . Noise is another issue.

Theatricality the first and the last would produce about the same noise and DOF and field of view . ( Assuming 2 stops advantage for the FF)

With the second having the least noise and shallowest DOF with the same field of view.

It's all in the 2 Stops.

Now lets raise the sensor density to the same as the 4/3 camera. and what do we get. ?

Other than the second example having less DOF. A 64MP sensor would be about just as noisy on a FF never mind the corner and edge fall off , with the last example being the most noisy. The only advantage would be DOF control.

and display the photos at the same size. Assuming the sensors are roughly the same efficiency, in what way will the photos be similar and in what way will they be different?

T
Collin
(Aficionado Olympus DSLR )
http://collinbaxter.zenfolio.com/
http://www.pbase.com/collinbaxter
http://www.outdoorphoto.co.za/gallery/showgallery.php?ppuser=21652&username=collin
Life is not measured by the number of breaths we take, but by the moments that take our breath away. (George Carlin)
New Seventh Wonder of the World.
http://www.pbase.com/collinbaxter/image/95297052.jpg

 CollBaxter's gear list:CollBaxter's gear list
Canon PowerShot SX230 HS Olympus E-500 Olympus E-30 Olympus E-620 Olympus E-5 +15 more
bobn2
bobn2 Forum Pro • Posts: 62,700
Re: A simple Yes or No.

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is the same.

That depends what you mean by 'light transmission'. Think of it this way - if take a room with a single 10cm square window, now call the glazier in and replace the window with a 1m square one. Will the room be brighter or darker? Has the light passing per unit area of the window changed?

-- hide signature --

Bob

Great Bustard Forum Pro • Posts: 43,430
Re: A simple Yes or No.
1

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is.

The same f-ratio results in the same light per area on the sensor for a given scene luminance, shutter speed, and transmissivity of the lens (i.e. the difference between the f-stop and t-stop).

But saying "a F/2.8 lens is a F/2.8 lens as far as light transmission" is misleading, 'cause an f/2.8 lens on 4/3 does *not* transmit the same amount of light to the sensor as an f/2.8 lens on FF.

As to the DOF we will all agree that DOF at the same F stop on different size senors are different. ( Hell I have been on this forum long enough to understand that) . Noise is another issue.

They are the same issue, actually. You see, for a given scene, perspective, framing, and shutter speed, it is the aperture (entrance pupil) diameter that determines the DOF and the total amount of light falling on the sensor, and thus, in combination with sensor efficiency, the noise.

Theatricality the first and the last would produce about the same noise and DOF and field of view . ( Assuming 2 stops advantage for the FF)

The "theoretically" is based on assuming the same sensor efficiency, which is usually fairly close for sensors of the same generation.

With the second having the least noise and shallowest DOF with the same field of view.

Specifically, half the noise and half the DOF.

It's all in the 2 Stops.

Yep.  In practice, just as a sharper lens on 4/3 reduces the resolution advantage of FF, a more efficient sensor on 4/3 will reduce the noise advantage of FF.  Likewise, a sharper lens on FF can extend the resolution advantage just as a more efficient sensor can extend the noise advantage.

I would say that, at higher ISOs, the advantage of modern FF over modern mFT is about 1.5 stops.

Now lets raise the sensor density to the same as the 4/3 camera. and what do we get. ?

The exact same thing, assuming, of course, that the higher density sensor is equally efficient.

Other than the second example having less DOF. A 64MP sensor would be about just as noisy on a FF never mind the corner and edge fall off , with the last example being the most noisy. The only advantage would be DOF control.

Consider the D600 vs the D800. The D800 has 50% more pixels than the D600. Is it more noisy?

bobn2
bobn2 Forum Pro • Posts: 62,700
Re: A simple Yes or No.

Great Bustard wrote:

Now lets raise the sensor density to the same as the 4/3 camera. and what do we get. ?

The exact same thing, assuming, of course, that the higher density sensor is equally efficient.

See for real here

http://www.dpreview.com/forums/thread/3612689?page=7#forum-post-53009511

In this case the FF camera actually has a higher density sensor than the FT. The efficiency thing isn't so out of order, according to Kodak, the E-1 sensor has a 34% QE in the green, so the D800 doesn't have a stop on it, at least as far as the brighter bits go. Neither of them can match the density of the 1/2.4" sensor obviously (and being BSI, that has the highest efficiency).

-- hide signature --

Bob

CollBaxter
CollBaxter Forum Pro • Posts: 12,724
Re: A simple Yes or No.

bobn2 wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is the same.

That depends what you mean by 'light transmission'. Think of it this way - if take a room with a single 10cm square window, now call the glazier in and replace the window with a 1m square one. Will the room be brighter or darker? Has the light passing per unit area of the window changed?

Lest keep things equal.

Firstly you are assuming the rooms are the same size and what size room do we want to light. So lets keep things equal as your example used a factor of 100 where as with 4/3 we a using a factor or 4.IN your example the room would have to be 100 times smaller. ( I don't think there is a sensor that small)

Just a question . With a pinhole camera assuming film of the same ISO and one box is 4X4" and the other is 8X8" with the film the same size. What would be the ratio of the hole size to get the same exposure using the same time on both boxes ?

-- hide signature --

Collin
(Aficionado Olympus DSLR )
http://collinbaxter.zenfolio.com/
http://www.pbase.com/collinbaxter
http://www.outdoorphoto.co.za/gallery/showgallery.php?ppuser=21652&username=collin
Life is not measured by the number of breaths we take, but by the moments that take our breath away. (George Carlin)
New Seventh Wonder of the World.
http://www.pbase.com/collinbaxter/image/95297052.jpg

 CollBaxter's gear list:CollBaxter's gear list
Canon PowerShot SX230 HS Olympus E-500 Olympus E-30 Olympus E-620 Olympus E-5 +15 more
bobn2
bobn2 Forum Pro • Posts: 62,700
Re: A simple Yes or No.

CollBaxter wrote:

bobn2 wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is the same.

That depends what you mean by 'light transmission'. Think of it this way - if take a room with a single 10cm square window, now call the glazier in and replace the window with a 1m square one. Will the room be brighter or darker? Has the light passing per unit area of the window changed?

Lest keep things equal.

The depends on which things are being kept 'equal'. In this case, we're talking about the window, and the light transmission through it.

Firstly you are assuming the rooms are the same size and what size room do we want to light.

The rooms are the same size.

So lets keep things equal as your example used a factor of 100 where as with 4/3 we a using a factor or 4.IN your example the room would have to be 100 times smaller. ( I don't think there is a sensor that small)

I don't think that the number matters so much, make it 4, 2 or whatever, the principle is the same

Just a question . With a pinhole camera assuming film of the same ISO and one box is 4X4" and the other is 8X8" with the film the same size. What would be the ratio of the hole size to get the same exposure using the same time on both boxes ?

That is a completely different question. I say the room is the same size, because you will view the final image the same size.

As for 'same ISO', that's only as sensible constraint if you know what it means. What do you think it means?

-- hide signature --

Bob

CollBaxter
CollBaxter Forum Pro • Posts: 12,724
Re: A simple Yes or No.

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is.

The same f-ratio results in the same light per area on the sensor for a given scene luminance, shutter speed, and transmissivity of the lens (i.e. the difference between the f-stop and t-stop).

But saying "a F/2.8 lens is a F/2.8 lens as far as light transmission" is misleading, 'cause an f/2.8 lens on 4/3 does *not* transmit the same amount of light to the sensor as an f/2.8 lens on FF.

As to the DOF we will all agree that DOF at the same F stop on different size senors are different. ( Hell I have been on this forum long enough to understand that) . Noise is another issue.

They are the same issue, actually. You see, for a given scene, perspective, framing, and shutter speed, it is the aperture (entrance pupil) diameter that determines the DOF and the total amount of light falling on the sensor, and thus, in combination with sensor efficiency, the noise.

Theatricality the first and the last would produce about the same noise and DOF and field of view . ( Assuming 2 stops advantage for the FF)

The "theoretically" is based on assuming the same sensor efficiency, which is usually fairly close for sensors of the same generation.

With the second having the least noise and shallowest DOF with the same field of view.

Specifically, half the noise and half the DOF.

It's all in the 2 Stops.

Yep. In practice, just as a sharper lens on 4/3 reduces the resolution advantage of FF, a more efficient sensor on 4/3 will reduce the noise advantage of FF. Likewise, a sharper lens on FF can extend the resolution advantage just as a more efficient sensor can extend the noise advantage.

I would say that, at higher ISOs, the advantage of modern FF over modern mFT is about 1.5 stops.

Now lets raise the sensor density to the same as the 4/3 camera. and what do we get. ?

The exact same thing, assuming, of course, that the higher density sensor is equally efficient.

Other than the second example having less DOF. A 64MP sensor would be about just as noisy on a FF never mind the corner and edge fall off , with the last example being the most noisy. The only advantage would be DOF control.

Consider the D600 vs the D800. The D800 has 50% more pixels than the D600. Is it more noisy?

You can't have your cake and eat it. When you use words like assuning equal eficencey.

" if the sensors are equally efficient? " its up near the top somewhere.

If you want to compare a 10 year old sensor to a modern sensor we are just fish paste , fish pasting around here for the sake of fish pasting.

Lets keep things equal with the theoretical and equal senors. Lets take your FF and chop it in 4 bits. Let not talk about a E-1 sensor as that's like comparing a model T Ford to the latest Ford  models.

We talk light transmission you cloud it with area efficacy and the old DOF thing.

A f/2 lens is a f/2 lens

-- hide signature --

Collin
(Aficionado Olympus DSLR )
http://collinbaxter.zenfolio.com/
http://www.pbase.com/collinbaxter
http://www.outdoorphoto.co.za/gallery/showgallery.php?ppuser=21652&username=collin
Life is not measured by the number of breaths we take, but by the moments that take our breath away. (George Carlin)
New Seventh Wonder of the World.
http://www.pbase.com/collinbaxter/image/95297052.jpg

 CollBaxter's gear list:CollBaxter's gear list
Canon PowerShot SX230 HS Olympus E-500 Olympus E-30 Olympus E-620 Olympus E-5 +15 more
CollBaxter
CollBaxter Forum Pro • Posts: 12,724
Re: A simple Yes or No.

bobn2 wrote:

CollBaxter wrote:

bobn2 wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is the same.

That depends what you mean by 'light transmission'. Think of it this way - if take a room with a single 10cm square window, now call the glazier in and replace the window with a 1m square one. Will the room be brighter or darker? Has the light passing per unit area of the window changed?

Lest keep things equal.

The depends on which things are being kept 'equal'. In this case, we're talking about the window, and the light transmission through it.

Firstly you are assuming the rooms are the same size and what size room do we want to light.

The rooms are the same size.

So lets keep things equal as your example used a factor of 100 where as with 4/3 we a using a factor or 4.IN your example the room would have to be 100 times smaller. ( I don't think there is a sensor that small)

I don't think that the number matters so much, make it 4, 2 or whatever, the principle is the same

Just a question . With a pinhole camera assuming film of the same ISO and one box is 4X4" and the other is 8X8" with the film the same size. What would be the ratio of the hole size to get the same exposure using the same time on both boxes ?

That is a completely different question. I say the room is the same size, because you will view the final image the same size.

As for 'same ISO', that's only as sensible constraint if you know what it means. What do you think it means?

That is filled  with ambiguities.

Any way guys I am off to bed it's midnight here.

Cheers

-- hide signature --

Collin
(Aficionado Olympus DSLR )
http://collinbaxter.zenfolio.com/
http://www.pbase.com/collinbaxter
http://www.outdoorphoto.co.za/gallery/showgallery.php?ppuser=21652&username=collin
Life is not measured by the number of breaths we take, but by the moments that take our breath away. (George Carlin)
New Seventh Wonder of the World.
http://www.pbase.com/collinbaxter/image/95297052.jpg

 CollBaxter's gear list:CollBaxter's gear list
Canon PowerShot SX230 HS Olympus E-500 Olympus E-30 Olympus E-620 Olympus E-5 +15 more
bobn2
bobn2 Forum Pro • Posts: 62,700
Re: A simple Yes or No.

CollBaxter wrote:

bobn2 wrote:

CollBaxter wrote:

bobn2 wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise if the sensors are equally efficient?

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is the same.

That depends what you mean by 'light transmission'. Think of it this way - if take a room with a single 10cm square window, now call the glazier in and replace the window with a 1m square one. Will the room be brighter or darker? Has the light passing per unit area of the window changed?

Lest keep things equal.

The depends on which things are being kept 'equal'. In this case, we're talking about the window, and the light transmission through it.

Firstly you are assuming the rooms are the same size and what size room do we want to light.

The rooms are the same size.

So lets keep things equal as your example used a factor of 100 where as with 4/3 we a using a factor or 4.IN your example the room would have to be 100 times smaller. ( I don't think there is a sensor that small)

I don't think that the number matters so much, make it 4, 2 or whatever, the principle is the same

Just a question . With a pinhole camera assuming film of the same ISO and one box is 4X4" and the other is 8X8" with the film the same size. What would be the ratio of the hole size to get the same exposure using the same time on both boxes ?

That is a completely different question. I say the room is the same size, because you will view the final image the same size.

As for 'same ISO', that's only as sensible constraint if you know what it means. What do you think it means?

That is filled with ambiguities.

No more (in fact considerably less) than what you said, to the point where I would say that comment is simply an evasion.

Any way guys I am off to bed it's midnight here.

Not going to say what 'ISO' is and why you think it's important that is is 'equal'?

-- hide signature --

Bob

bobn2
bobn2 Forum Pro • Posts: 62,700
Re: A simple Yes or No.

CollBaxter wrote:

If you want to compare a 10 year old sensor to a modern sensor we are just fish paste , fish pasting around here for the sake of fish pasting.

Lets keep things equal with the theoretical and equal senors. Lets take your FF and chop it in 4 bits. Let not talk about a E-1 sensor as that's like comparing a model T Ford to the latest Ford models.

It depends on what you look at. In terms of quantum efficiency the E-1 is not so bad, it goes to 34%, while the modern CMOS are at around 50% or a bit more, so about 1/2 stop worse or so - not too serious. If course it's far worse in read noise, but ignore the noise in the shadows, and you get a pretty good idea of how it's doing.

-- hide signature --

Bob

pwilly
pwilly Senior Member • Posts: 1,176
Re: Um...
1

bobn2 wrote:

Great Bustard wrote:

A 300mm f/2.8 m43 lens which creates an image circle with half the diameter of a 300mm f/2.8 FF lens will deliver the same amount of total light to the sensor.

No. A 300 / 2.8 will put the same density of light (same light per area) on the sensor regardless of the format, but not the same total amount of light.

And also, the image circle isn't very tightly coupled to the format in use. I would guess that if you removed the baffles, most SHG lenses would produce pretty much a FF image circle. It's one of the things that is done to give 'edge to edge' sharpness, make the image circle large and just use the centre of it. Long FL lenses in particular tend to have big image circles.

If you removed the baffles you would need to call the ghost and flair busters!

While the area will be smaller the density of light will be higher.

No. The same f-ratio results in the same density, regardless of format, but not the same total amount of light on the sensor.

Isn't this what the speed boosters do?

Speedboosters (focal reducers) compress the larger image circle into a smaller image circle, and thus put the same total amount of light on the sensor. For example, a 0.5x FR will result in half the focal length, but the aperture (entrance pupil) diameter remains the same, so the relative aperture (f-ratio) is halved since the focal length is halved.

They reduce the whole image, and the image circle as a result. Their operation without vignetting depends on a large enough image circle.

-- hide signature --

Bob

-- hide signature --

Paul
Just an old dos guy

Great Bustard Forum Pro • Posts: 43,430
Re: A simple Yes or No.

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

CollBaxter wrote:

Great Bustard wrote:

gsergei wrote:

Or why the light meter doesn't care.

Hello, again.

Let me repeat my point:

Given the same light source conditions and ISO setting the illumination, measured in lumens, received by any size of sensor is equal across all formats (no Ifs , no buts) , when cameras are set to the same A , S, ISO values. So, in practical terms this means, that the illumination received by my tiny c7070 at 125/5.6 and ISO 100 is exactly the same as on the so called FF sensor camera set to the same values. This will result in the same picture brightness/darkness , subject to DR and noise differences.

No one that I'm aware of claims that f/2 will not result in the same exposure regardless of format or focal length for a given scene luminance and shutter speed.

Please, do not feed me things like "amount of light", "sensor area", "light power" , "bigger lens opening" etc. and try to operate , using known physical terms and concepts.

If the difference between the amount of light per area that falls on the sensor (exposure), and the total amount of light the sensor records is difficult to understand, well...

Is the amount/intensity of light on a say a square cm at the center 4/3 , APS-C , APS-H , 1 inch , FF , 36X49 sensors at say f/2.8 not equal ?

A simple Yes or No.

Yes. Now, if you would return the favor:

For a given perspective, framing, and shutter speed will f/2 on 4/3 result in a photo with the same DOF as f/4 on FF as well as project the same total amount of light on the sensor, resulting in the same noise

A simple Yes or No.

Now, if I could trouble you for one more yes/no question:

We take a pic of the same scene from the same position at:

  • 50mm f/2 1/200 ISO 400 on 4/3
  • 100mm f/2 1/200 ISO 400 on FF
  • 100mm f/4 1/200 ISO 1600 on FF

Thanks for the answer . So a F/2.8 lens is a F/2.8 lens as far as light transmission , no mater what the sensor size is.

The same f-ratio results in the same light per area on the sensor for a given scene luminance, shutter speed, and transmissivity of the lens (i.e. the difference between the f-stop and t-stop).

But saying "a F/2.8 lens is a F/2.8 lens as far as light transmission" is misleading, 'cause an f/2.8 lens on 4/3 does *not* transmit the same amount of light to the sensor as an f/2.8 lens on FF.

As to the DOF we will all agree that DOF at the same F stop on different size senors are different. ( Hell I have been on this forum long enough to understand that) . Noise is another issue.

They are the same issue, actually. You see, for a given scene, perspective, framing, and shutter speed, it is the aperture (entrance pupil) diameter that determines the DOF and the total amount of light falling on the sensor, and thus, in combination with sensor efficiency, the noise.

Theatricality the first and the last would produce about the same noise and DOF and field of view . ( Assuming 2 stops advantage for the FF)

The "theoretically" is based on assuming the same sensor efficiency, which is usually fairly close for sensors of the same generation.

With the second having the least noise and shallowest DOF with the same field of view.

Specifically, half the noise and half the DOF.

It's all in the 2 Stops.

Yep. In practice, just as a sharper lens on 4/3 reduces the resolution advantage of FF, a more efficient sensor on 4/3 will reduce the noise advantage of FF. Likewise, a sharper lens on FF can extend the resolution advantage just as a more efficient sensor can extend the noise advantage.

I would say that, at higher ISOs, the advantage of modern FF over modern mFT is about 1.5 stops.

Now lets raise the sensor density to the same as the 4/3 camera. and what do we get. ?

The exact same thing, assuming, of course, that the higher density sensor is equally efficient.

Other than the second example having less DOF. A 64MP sensor would be about just as noisy on a FF never mind the corner and edge fall off , with the last example being the most noisy. The only advantage would be DOF control.

Consider the D600 vs the D800. The D800 has 50% more pixels than the D600. Is it more noisy?

You can't have your cake and eat it.  When you use words like assuning equal eficencey." if the sensors are equally efficient? " its up near the top somewhere.

Well, you can go to Sensorgen and see a partial list of sensor efficiencies.  You will note, for example, the the 5D2 and E5 sensors are almost exactly the same efficiency, as are the 6D and EM5 sensors.

If you want to compare a 10 year old sensor to a modern sensor we are just fish paste , fish pasting around here for the sake of fish pasting.

I'm not the one wanting to make such a comparison.  But, are you really going to argue that f/2.8 on an E1 is not f/2.8 on an EM1 because the EM1 sensor is more efficient?

Lets keep things equal with the theoretical and equal senors. Lets take your FF and chop it in 4 bits. Let not talk about a E-1 sensor as that's like comparing a model T Ford to the latest Ford models.

OK.

We talk light transmission you cloud it with area efficacy and the old DOF thing.

What do you mean by "light transmission"?  Do you mean the light per area falling on the sensor or the amount of light falling on the sensor?  You see, these are two very different things, and, in fact, at the core of the matter, and people are either ignorant of this distinction and what effect it has on the visual properties of the recorded photo, or they are intentionally deceptive in failing to acknowledge this simple concept.

A f/2 lens is a f/2 lens

And a 50mm lens is a 50mm lens.  But just as the effect of 50mm on 4/3 has the same effect as 100mm on FF, in terms of the visual properties of the photo, f/2 on 4/3 has the same effect as f/4 on FF, in terms of the visual properties of the photo.

You said ealier "You can't have your cake and eat it", and yet it is you, and all the other people who argue against Equivalence, that are trying to have their cake and eat it by completely sidestepping (either by ignorance or malice) the difference between the amount of light per area that falls on the sensor and the total amount of light that falls on the sensor, and what this has to do with the visual properties of the recorded photo.

And, FYI, while I take every care to say, for example, that 50mm f/2 on 4/3 is equivalent to (as opposed to "equal to") 100mm f/4 on FF, the fact of the matter is that a 50 / 2 lens with a 2x TC does equal a 100 / 4 lens, and if you put it in front of a FF sensor, it would take the same photos as the bare 50 / 2 lens in front of a 4/3 sensor.

Keyboard shortcuts:
FForum MMy threads