Full frame equivalences for lenses

[DJ STU-C]

Rather than quoting walls of text, ill pose some basic questions around the exposure triangle.

Can someone tell me, as a beginner, what is wrong with using this as a way of showing the relationship between the 3 main functions of a camera, and using it as a tool to learn how my camera works.

It's not an inherently bad tool for initially learning, but it does risk being a little misleading.

It seems to me people want to rubbish the exposure triangle for nothing more than reasons of petty snobbery, to simply start an argument, or to somehow come across sas having some kind of superior knowledge, and honestly I have no idea why. It's a simple drawing/table that lets people understand the physical relationship between the 3 settings, and how changing one of them impacts the final image.

It's more that it risks embedding some misunderstandings.

The amount of light your sensor is exposed to is the fundamental thing that determines your image quality. Exposure is defined by the shutter speed, the aperture and the illumination level.

ISO is essentially 'how light do I want my image to look.' It's not an equal partner in the equation.

For instance, the diagram above shows grain increasing with ISO. And that risks giving the impression that it's increasing the ISO setting that causes the grain, which is not true.

Grain (actually noise), increases in the situations in which you find yourself increasing ISO (when there's not enough exposure, either because of shutter speed, aperture or illumination level). It's not caused by increasing ISO.

The concern about the exposure triangle beyond an initial introduction is that it muddies cause and effect and can lead to some strange misunderstandings about why images are noisy and how to address that.

Set ISO to 0 and you get no exposure, increase it in line with the other 2 settings and you get an exposure. Removing it from the learning process offers nothing and claiming this 'triangle' of exposure is incorrect offers nothing.

It's a bit gatekeepery at the very least.

I can't speak for everyone (and I'm ambivalent about the exposure triangle concept, personally), but it's usually intended as the opposite: trying to help avoid embedding misunderstanding.

Richard - DPReview.com

But id rather have a simple graphic image like that above to show a beginner what each of the 3 settings do and how they help them get a final image. Imagine taking ISO out of that image and asking someone to expose a shot correctly, they would give up after 30 minutes of bad shots.

Whereas you can use this to explain that you will need to increase it if you want to say freeze a subject as the light lowers, or you want to increase depth of field, or you have decreased the depth of field to its limit and your shot is still too dark. Not including it as a 3 way set of functions that need to be juggled is far more misleading than the technicalities around what causes a grainy photo.

--
Stu-C

Stu

Explore Stu’s 298 photos on Flickr!

flickr.com

 

[DJ STU-C]

Assuming equal sensor technology

Who has equal sensor technology to Fujifilm?

with a different color filter array.

Thanks, so not the same then.

Basically the same. The underlying hardware is definitely the same. With the medium format sensors, those use a standard Bayer color filter array and are the same Sony sensor used in other medium format cameras.

But not the same, so there are variables that can and will impact how the final image is displayed. Much in the same way a Canon sensor will differ from a Sony one, or a bespoke Nikon sensor will differ from the other two. Given how important the processor is in the process of producing the final image, that also plays a part in this too.

So your assumption about sensor technology is completely wrong, im sorry.

The camera companies cant even operate using the same ISO standards.

--
Stu-C
https://flickr.com/photos/138087015@N02/

 

[Morris0]

Richard Butler has written an excellent explanation of equivalence with plenty of sample images....

https://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

Here is a video by Simon d'Entremont, a professional wildlife and nature photographer, that covers the same subject and there are some very interesting contradictions. For example bokeh and DOF for the same lens at the same settings shot on both full frame and APS-C. Skip to 9 minutes in to see this and why I have been disagreeing.

There is a lot of agreement between the video and what Richard states yet the example of DOF and exposure with the same lens and what happens when you crop is what people here don't seem to get.

Morris

 

[nnowak]

Assuming equal sensor technology

Who has equal sensor technology to Fujifilm?

with a different color filter array.

Thanks, so not the same then.

Basically the same. The underlying hardware is definitely the same. With the medium format sensors, those use a standard Bayer color filter array and are the same Sony sensor used in other medium format cameras.

But not the same, so there are variables that can and will impact how the final image is displayed. Much in the same way a Canon sensor will differ from a Sony one, or a bespoke Nikon sensor will differ from the other two. Given how important the processor is in the process of producing the final image, that also plays a part in this too.

So your assumption about sensor technology is completely wrong, im sorry.

The camera companies cant even operate using the same ISO standards.

Are there sensor technology differences that impact quality? Yes. In the context of modern sensor produced in the last few year, are the differences meaningful? No. The image quality differences between any APS-C sensor and any full frame sensor are far greater than the difference between a Canon APS-C sensor and a Fuji APS-C sensor.

The one exception to this would be the Sony A9 III with its new global shutter sensor, but that is a sensor with significantly different technology.

 

[Bill Ferris]

The DPR Studio Scene does a great job of illustrating the light-gatgering potential of a larger sensor working with the same exposure as a smaller sensor. Here's one example:

https://www.dpreview.com/reviews/image-comparison/fullscreen?attr18=lowlight&attr13_0=fujifilm_gfx50sii&attr13_1=sony_a7iv&attr13_2=nikon_z50ii&attr13_3=omsystem_om1&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=6400&attr16_1=6400&attr16_2=6400&attr16_3=6400&attr126_3=1&normalization=compare&widget=1&x=0&y=0

 

[nnowak]

Maybe I should explain WHY I was asking the question.

I hate noise with a vengeance. I love clean photos.

I have an XT-5 with various (OK, far too many) lenses.

I was out at a prog concert on Sunday night and taking pictures with the X-T5 and my 16-55F2.8. Of course, with the low light, the ISO was up at 4,000, 8,000, 12,800 and the resultant images were noisy.

So, I put them through Photoshop to get rid of the noise - which it does rather well, except that, to me, the images look artificial - especially peoples skin.

So, I was wondering, if I got a FF equivalent camera which (I would hope) had less noise at the same ISO, what lens would I need to match the 16-55 F2.8. BUT - if the equivalant doubles the ISO, what's the point?

It was purely a brain exercise because there's no way I can justify paying many thousands to get something equivalent or slightly better than my X-T5 - which, by the way, I love for everything else - especially the crop factor with 40mp.

The only realistic way to reduce noise in your sample images would be to accept a shallower depth of field. This could come from an f/1.4 prime on your current camera, or a full frame camera with a lens that is f/2.8, or brighter. Either way, you will get a thinner DoF. Lowering your shutter speed would also be an option, but then there would be more motion blur.

 

[DJ STU-C]

Assuming equal sensor technology

Who has equal sensor technology to Fujifilm?

with a different color filter array.

Thanks, so not the same then.

Basically the same. The underlying hardware is definitely the same. With the medium format sensors, those use a standard Bayer color filter array and are the same Sony sensor used in other medium format cameras.

But not the same, so there are variables that can and will impact how the final image is displayed. Much in the same way a Canon sensor will differ from a Sony one, or a bespoke Nikon sensor will differ from the other two. Given how important the processor is in the process of producing the final image, that also plays a part in this too.

So your assumption about sensor technology is completely wrong, im sorry.

The camera companies cant even operate using the same ISO standards.

Are there sensor technology differences that impact quality? Yes. In the context of modern sensor produced in the last few year, are the differences meaningful? No. The image quality differences between any APS-C sensor and any full frame sensor are far greater than the difference between a Canon APS-C sensor and a Fuji APS-C sensor.

The one exception to this would be the Sony A9 III with its new global shutter sensor, but that is a sensor with significantly different technology.

So the image quality difference between a 15yr old Full frame camera and a 2025 APS-C camera will be great will it?



Can you provide some examples to display this.

 

[Richard Butler]

DJ STU-C wrote

But id rather have a simple graphic image like that above to show a beginner what each of the 3 settings do and how they help them get a final image. Imagine taking ISO out of that image and asking someone to expose a shot correctly, they would give up after 30 minutes of bad shots.

I didn't say it shouldn't be used as an introduction. But ideally it would be made clear that not all three are equal in their role.

Whereas you can use this to explain that you will need to increase it if you want to say freeze a subject as the light lowers, or you want to increase depth of field, or you have decreased the depth of field to its limit and your shot is still too dark. Not including it as a 3 way set of functions that need to be juggled is far more misleading than the technicalities around what causes a grainy photo.

Arguably two should be juggled and the third set to compensate but I haven't advocated for not discussing ISO (or for not using the exposure triangle as a first step).

Richard - DPReview.com

 

[Richard Butler]

There is a lot of agreement between the video and what Richard states yet the example of DOF and exposure with the same lens and what happens when you crop is what people here don't seem to get.

If you crop an APS-C region out of any sized sensor, you have effectively used an APS-C camera, so you get the same results. That's not what was being discussed.

The OP asked if his 16-55mm F2.8 lens is equivalent to a 24-80mm F4 lens used on full frame. The answer is yes.

Let's narrow it down to just the 24mm setting on the APS-C camera, to keep things simple.

If you take a photo at 24mm on the APS-C camera and at 24mm on a full-frame camera from the same position, they will be radically different photos: you've either framed badly on the full-frame one and included lots of extra stuff that you need to crop away, or you've cut the edges off the scene on the APS-C shot.

They're simply not the same photo. One is presumably the photo you want, the other isn't.

If you crop in to the APS-C region of the full-frame camera, then you've effectively used an APS-C camera and should probably think hard about your composition or lens choice.

Which is the point.

If I stand in the same position (because there are plenty of instances where you can't move freely to whatever location you want), and want to take a photo with the same framing as the 24mm on APS-C, you'd need to zoom to around 36mm on the full-frame camera.

That accounts for what the OP was saying in terms of the focal lengths being equivalent and that's why we're not comparing 24mm on both systems: because they'd take different photos.

And that's all video says too: if you use a different sensor size, you'll end up using different lenses (potentially with different aperture diameters), and it's the different lens, not the different sensor size that makes the difference.

Obviously it's the combination of sensor size and appropriate lens that has the impact we're discussing (hence the comparison between the 16-55mm lens and a hypothetical different lens with different focal lengths on a different system).

It's wrong to say it's caused by sensor size alone, but it's equally peculiar to say it's only caused by focal length alone because, while it's strictly true, it presupposes that you're picking a focal length with no consideration of what sensor you're mounting it on, which is just not how any photographer I've ever met thinks.

Richard - DPReview.com

 

[nnowak]

Richard Butler has written an excellent explanation of equivalence with plenty of sample images....

https://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

Here is a video by Simon d'Entremont, a professional wildlife and nature photographer, that covers the same subject and there are some very interesting contradictions. For example bokeh and DOF for the same lens at the same settings shot on both full frame and APS-C. Skip to 9 minutes in to see this and why I have been disagreeing.

Actually, those sample photos of the toy owl from the 9 minute mark completely agree with what Richard wrote. If you look at the uncropped full frame image next to the crop sensor image, the apparent DoF is different. This matches with any DoF calculator that shows 50mm f/2 on full frame will have a greater DoF than 50mm f/2 on crop when shot at the same distance.

When the full frame image was cropped to match the crop sensor image, the DoF of the 2 images now looks the same. Yes, the apparent DoF changed due to the crop.

Here is a simple "why".... Take any image and open it up on your computer. Pick any in focus area of your image and start zooming in. At some zoom level, an area that looked sharp will start to look blurry. Maybe it will happen at 100%, or maybe not until 800%, but it will definitely start to look blurry. Back to the sample from above...that cropped image is magnified by 150%. Because of that additional magnification, areas that were borderline in focus now look blurry and the apparent DoF looks thinner.

The same is also true for noise levels because the magnification makes the noisy pixels larger and more visible.

It doesn't matter if the crop happens at the sensor fab, in the camera, or in your editing software, the end result is still the same.

 

[nnowak]

Assuming equal sensor technology

Who has equal sensor technology to Fujifilm?

with a different color filter array.

Thanks, so not the same then.

Basically the same. The underlying hardware is definitely the same. With the medium format sensors, those use a standard Bayer color filter array and are the same Sony sensor used in other medium format cameras.

But not the same, so there are variables that can and will impact how the final image is displayed. Much in the same way a Canon sensor will differ from a Sony one, or a bespoke Nikon sensor will differ from the other two. Given how important the processor is in the process of producing the final image, that also plays a part in this too.

So your assumption about sensor technology is completely wrong, im sorry.

The camera companies cant even operate using the same ISO standards.

Are there sensor technology differences that impact quality? Yes. In the context of modern sensor produced in the last few year, are the differences meaningful? No. The image quality differences between any APS-C sensor and any full frame sensor are far greater than the difference between a Canon APS-C sensor and a Fuji APS-C sensor.

The one exception to this would be the Sony A9 III with its new global shutter sensor, but that is a sensor with significantly different technology.

So the image quality difference between a 15yr old Full frame camera and a 2025 APS-C camera will be great will it?

How are those two "equal sensor technology"?

 

[Morris0]

There is a lot of agreement between the video and what Richard states yet the example of DOF and exposure with the same lens and what happens when you crop is what people here don't seem to get.

If you crop an APS-C region out of any sized sensor, you have effectively used an APS-C camera, so you get the same results. That's not what was being discussed.

The OP asked if his 16-55mm F2.8 lens is equivalent to a 24-80mm F4 lens used on full frame. The answer is yes.

Let's narrow it down to just the 24mm setting on the APS-C camera, to keep things simple.

If you take a photo at 24mm on the APS-C camera and at 24mm on a full-frame camera from the same position, they will be radically different photos: you've either framed badly on the full-frame one and included lots of extra stuff that you need to crop away, or you've cut the edges off the scene on the APS-C shot.

They're simply not the same photo. One is presumably the photo you want, the other isn't.

If you crop in to the APS-C region of the full-frame camera, then you've effectively used an APS-C camera and should probably think hard about your composition or lens choice.

Which is the point.

If I stand in the same position (because there are plenty of instances where you can't move freely to whatever location you want), and want to take a photo with the same framing as the 24mm on APS-C, you'd need to zoom to around 36mm on the full-frame camera.

That accounts for what the OP was saying in terms of the focal lengths being equivalent and that's why we're not comparing 24mm on both systems: because they'd take different photos.

And that's all video says too: if you use a different sensor size, you'll end up using different lenses (potentially with different aperture diameters), and it's the different lens, not the different sensor size that makes the difference.

Obviously it's the combination of sensor size and appropriate lens that has the impact we're discussing (hence the comparison between the 16-55mm lens and a hypothetical different lens with different focal lengths on a different system).

It's wrong to say it's caused by sensor size alone, but it's equally peculiar to say it's only caused by focal length alone because, while it's strictly true, it presupposes that you're picking a focal length with no consideration of what sensor you're mounting it on, which is just not how any photographer I've ever met thinks.

Richard - DPReview.com

My issues with what some have said have had to do with exposure, not field of view. I don't think we disagree with the way FOV, DOF and exposure work and there relationship to sensor size.

Morris

 

[Morris0]

Richard Butler has written an excellent explanation of equivalence with plenty of sample images....

https://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

Here is a video by Simon d'Entremont, a professional wildlife and nature photographer, that covers the same subject and there are some very interesting contradictions. For example bokeh and DOF for the same lens at the same settings shot on both full frame and APS-C. Skip to 9 minutes in to see this and why I have been disagreeing.

Actually, those sample photos of the toy owl from the 9 minute mark completely agree with what Richard wrote. If you look at the uncropped full frame image next to the crop sensor image, the apparent DoF is different. This matches with any DoF calculator that shows 50mm f/2 on full frame will have a greater DoF than 50mm f/2 on crop when shot at the same distance.

When the full frame image was cropped to match the crop sensor image, the DoF of the 2 images now looks the same. Yes, the apparent DoF changed due to the crop.

They look the same as they are the same and Simon states this.

Here is a simple "why".... Take any image and open it up on your computer. Pick any in focus area of your image and start zooming in. At some zoom level, an area that looked sharp will start to look blurry. Maybe it will happen at 100%, or maybe not until 800%, but it will definitely start to look blurry. Back to the sample from above...that cropped image is magnified by 150%. Because of that additional magnification, areas that were borderline in focus now look blurry and the apparent DoF looks thinner.

There is much more to it than just DOF

The same is also true for noise levels because the magnification makes the noisy pixels larger and more visible.

Watch the whole video. Noise is the result of pixel size as well as other factors.

It doesn't matter if the crop happens at the sensor fab, in the camera, or in your editing software, the end result is still the same.

From the same image I agree. Add any other variable and it's complicated way beyond the things this thread is about.

Morris

 

[Bill Ferris]

Maybe I should explain WHY I was asking the question.

I hate noise with a vengeance. I love clean photos.

I have an XT-5 with various (OK, far too many) lenses.

I was out at a prog concert on Sunday night and taking pictures with the X-T5 and my 16-55F2.8. Of course, with the low light, the ISO was up at 4,000, 8,000, 12,800 and the resultant images were noisy.

So, I put them through Photoshop to get rid of the noise - which it does rather well, except that, to me, the images look artificial - especially peoples skin.

So, I was wondering, if I got a FF equivalent camera which (I would hope) had less noise at the same ISO, what lens would I need to match the 16-55 F2.8. BUT - if the equivalant doubles the ISO, what's the point?

This is where equivalence may not be an obvious pathway to address your issue. I say this because equivalence is a tool for determining which settings different format cameras can use to make the same photo. Your goal is to use a different format system to make a different photo; one with less noise and better overall quality.

Once one understands the fundamental principles of equivalence, it becomes easier to address your need. Here's the key: equivalent systems work with the same size lens entrance pupil. To achieve the results you want, you need a lens with a larger entrance pupil.

How much larger? Big enough to mage a significant difference in image quality. Personally, I'd place that threshold at a 1-stop increase in light-gathering. The relative light-gathering of two systems is equal to the square of their relative apertures. A lens with an entrance pupil 1.4x the size of another collects twice as much light. That's a full stop advantage.

The 16-55mm f/2.8 has a (16mm/2.8=5.7mm) 6mm entrance pupil wide open at 16mm and a (55mm/2.8=19.6mm) 20mm entrance pupil wide open at 55mm. Assuming you're already using the slowest practical shutter speed, there are two paths to putting another stop of light on the sensor. One is to upgrade to a 16-55mm f/2 lens. That would give you an entrance pupil range of 8mm (40% larger than 5.7mm) to 28mm (40% larger than 20mm).

Is there such a lens for Fujifilm? I don't know. If there isn't, would a couple of f/2 primes meet your needs?

In full frame, a 24-80mm f2.8 lens would address your issue. The longer focal lengths would match the framing your current lenses provides. The larger sensor surface area would allow you to collect more total light at the same f-stop.

24-70mm f/2.8 zooms in full frame are common; common and a bit pricey. You can also look for a couple of faster primes.

It was purely a brain exercise because there's no way I can justify paying many thousands to get something equivalent or slightly better than my X-T5 - which, by the way, I love for everything else - especially the crop factor with 40mp.

Cost, size, weight and usability are often factors influencing one's choice of format.

Here's a couple of processed images.

Graham, lead guitarist, in full flow.

Charlie, lead singer.

You mention Photoshop. If that is where you do most of your photo processing? I work mostly in Lightroom and would use the Enhance tool at a setting of about 30 to sharpen and cleanup a photo made at ISO 6400. I don't know which noise reduction/sharpening tool you use but, if you've got access to Enhance, I'd recommend starting there.

Good luck.

--
Bill Ferris Photography
Flagstaff, AZ

 

[nnowak]

Rather than quoting walls of text, ill pose some basic questions around the exposure triangle.

Can someone tell me, as a beginner, what is wrong with using this as a way of showing the relationship between the 3 main functions of a camera, and using it as a tool to learn how my camera works.

It seems to me people want to rubbish the exposure triangle for nothing more than reasons of petty snobbery, to simply start an argument, or to somehow come across sas having some kind of superior knowledge, and honestly I have no idea why. It's a simple drawing/table that lets people understand the physical relationship between the 3 settings, and how changing one of them impacts the final image.

Set ISO to 0 and you get no exposure, increase it in line with the other 2 settings and you get an exposure. Removing it from the learning process offers nothing and claiming this 'triangle' of exposure is incorrect offers nothing.

It's a bit gatekeepery at the very least.

Equivalence is not "gatekeepery" and it is not in conflict with the exposure triangle. They are two very different concepts. I think most of the confusion in this discussion comes from people who think the exposure triangle equals equivalence.

Here are two equivalent exposures...

• micro 4/3 - 25mm, f/2.0, 1/100, ISO 100
• full frame - 50mm f/4.0, 1/00, ISO 400

In terms of the exposure triangle, only 1 of the 3 settings remains the same (shutter speed). However, in terms of angle of view, depth of field and noise levels, the images will look the same.

 

[guy_incognito1]

There is no formula for what each individual sees and how each individual interprets visual data.

Morris

I think the confusion is you are using the word equivalence in the english meaning of "the same" whereas everyone is using the photographic definition of the word equivalence, which has a set definition.

You may object to the fact that photographers of yore have chosen to use the english word "equivalence" for their narrow technical definition they call equivalance, but that is the way people are using it.

 

[Patographer]

This is the best video I've seen explaining the relationship between depth of field and sensor size.
(video is in Spanish)

 

[DJ STU-C]

Rather than quoting walls of text, ill pose some basic questions around the exposure triangle.

Can someone tell me, as a beginner, what is wrong with using this as a way of showing the relationship between the 3 main functions of a camera, and using it as a tool to learn how my camera works.

It seems to me people want to rubbish the exposure triangle for nothing more than reasons of petty snobbery, to simply start an argument, or to somehow come across sas having some kind of superior knowledge, and honestly I have no idea why. It's a simple drawing/table that lets people understand the physical relationship between the 3 settings, and how changing one of them impacts the final image.

Set ISO to 0 and you get no exposure, increase it in line with the other 2 settings and you get an exposure. Removing it from the learning process offers nothing and claiming this 'triangle' of exposure is incorrect offers nothing.

It's a bit gatekeepery at the very least.

Equivalence is not "gatekeepery" and it is not in conflict with the exposure triangle. They are two very different concepts. I think most of the confusion in this discussion comes from people who think the exposure triangle equals equivalence.

Here are two equivalent exposures...

• micro 4/3 - 25mm, f/2.0, 1/100, ISO 100
• full frame - 50mm f/4.0, 1/00, ISO 400

In terms of the exposure triangle, only 1 of the 3 settings remains the same (shutter speed). However, in terms of angle of view, depth of field and noise levels, the images will look the same.

Absolutely nothing to do with that conversation thread, and nobody said equivalence is gatekeeping, please read the whole thread back because we aren’t discussing equivalence at all.

--
Stu-C

Stu

Explore Stu’s 298 photos on Flickr!

flickr.com

 

[DJ STU-C]

Assuming equal sensor technology

Who has equal sensor technology to Fujifilm?

with a different color filter array.

Thanks, so not the same then.

Basically the same. The underlying hardware is definitely the same. With the medium format sensors, those use a standard Bayer color filter array and are the same Sony sensor used in other medium format cameras.

But not the same, so there are variables that can and will impact how the final image is displayed. Much in the same way a Canon sensor will differ from a Sony one, or a bespoke Nikon sensor will differ from the other two. Given how important the processor is in the process of producing the final image, that also plays a part in this too.

So your assumption about sensor technology is completely wrong, im sorry.

The camera companies cant even operate using the same ISO standards.

Are there sensor technology differences that impact quality? Yes. In the context of modern sensor produced in the last few year, are the differences meaningful? No. The image quality differences between any APS-C sensor and any full frame sensor are far greater than the difference between a Canon APS-C sensor and a Fuji APS-C sensor.

The one exception to this would be the Sony A9 III with its new global shutter sensor, but that is a sensor with significantly different technology.

So the image quality difference between a 15yr old Full frame camera and a 2025 APS-C camera will be great will it?

How are those two "equal sensor technology"?

You said ‘“the image quality difference between ANY APS-C sensor and ANY full frame sensor are far greater”

You seem to be not very good at reading, or choosing not to, one of the two.

 

[Morris0]

There is no formula for what each individual sees and how each individual interprets visual data.

Morris

I think the confusion is you are using the word equivalence in the english meaning of "the same" whereas everyone is using the photographic definition of the word equivalence, which has a set definition.

You may object to the fact that photographers of yore have chosen to use the english word "equivalence" for their narrow technical definition they call equivalance, but that is the way people are using it.

When people use the direct terms such as Field of View, there is agreement. The rest of equivalence as used by photographers leads to arguments, mis understandings and more just as we have here.

Morris