Calling all portrait photographers!

[Ysarex]

In order for it to be a fair comparison and so compare the effect of sensor size you have to take the same photograph. To do that with two different size sensor you must change focal length. And yes that focal length change will factor in but so does the sensor size. If you don't take the same photograph you have nothing to compare.

Joe

So you are saying that all other things being equal, two different sized sensors will produce a digital image with the same Depth of Field. By "all other things" I am referring to focal length, distance to subject, aperture, and uncropped or unenlarged images displayed at the images' native resolution. Obviously the view angles and actual sizes (in pixels) will differ between the images.

No. If you don't crop the FX sensor you have two different photos and the DOF between them is different. It's just not a helpful comparison because you have two different photos. Either way you'll get different DOF. 1. Don't crop the FX sensor image or 2.compare same photographs (requires FL change).

Joe

I'm done with the hijacking of this thread. My observations from any testing will be posted elsewhere.

Happy to have you along here.

 

[Derrel]

That British expression, "Christ on a bike!" keeps running through my brain as I read this thread...

Destin and Solarflare: If either of you you would like a real, scientific, and a fully accurate,correct,and total explanation of DOF as it relates to focal length and sensor size, here is the book that I learned this all from: This is the same, exact book I have owned since 1975...

https://www.amazon.com/Photographic-Principles-Practices-Harry-Asher/dp/B0026S6IHS

For $3.99 you can be made aware of the science underlying this wacky DOF thing...

 

[Ysarex]

But, if I am using an FX sensor in DX mode, isn't that the same as using DX sensor (and thus changing the Circle of Confusion)?

Exactly. You're cropping the FX sensor down to DX in the camera. Cropping the FX image after you've taken it does exactly the same thing and produces the same result. The DOF for a DX sensor is the same as the DOF for a DX sensor. If you want to compare the difference in DOF between a DX and FX sensor you have to in fact use the FX sensor uncropped and take the same photo with both cameras.

Joe

But in order to take the same photo with both cameras the image either has to be cropped or the full frame camera has to be moved closer. It’s impossible to take the same images without doing one or the other.

Not true -- you can change the lens focal length on one of the cameras. And in fact to do an appropriate same photograph comparison you'll have to do that. When you take the same photograph with two different sensor size cameras from the same place and at the same f/stop the DOF will be different between them. It will in part be due to the sensor size which will be accounted for in the calculations in the variable circle of confusion.

Joe

But changing focal length to match the field of view will make the DOF thinner. In order for it to be a fair comparison you cannot change focal length.

In order for it to be a fair comparison and so compare the effect of sensor size you have to take the same photograph. To do that with two different size sensor you must change focal length. And yes that focal length change will factor in but so does the sensor size. If you don't take the same photograph you have nothing to compare.

Joe

Joe - by changing any of those other factors to take the same photograph you cannot isolate the factor that is changing the depth of field. That isn’t how scientific experiments work.

You can only have one variable that changes, otherwise you have no idea what is actually causing the change.

The *only way* to create the same photo as a DX camera using an FX camera is to crop the FX image down to match the DX image.

In doing so, both images will appear *identical*

Therefore the sensor size does not physically affect DOF, other than by forcing you to change other variables to make the field of view the same.

Here's the variation due strictly to sensor size:

By repeating the same calculation for the DX camera but changing only the variable that accounts for sensor size I got a change in DOF from 3.98 ft to 6.28 ft. In all three cases the cameras are being used to take the same photograph. All three have different DOFs with the bottom one reporting a false value because the required value in the calculation to account for sensor size was deliberately incorrect.

Sensor size is a direct determinant of DOF. Otherwise try telling Don Fleming his math is wrong.

Joe

 

[Destin]

But, if I am using an FX sensor in DX mode, isn't that the same as using DX sensor (and thus changing the Circle of Confusion)?

Exactly. You're cropping the FX sensor down to DX in the camera. Cropping the FX image after you've taken it does exactly the same thing and produces the same result. The DOF for a DX sensor is the same as the DOF for a DX sensor. If you want to compare the difference in DOF between a DX and FX sensor you have to in fact use the FX sensor uncropped and take the same photo with both cameras.

Joe

But in order to take the same photo with both cameras the image either has to be cropped or the full frame camera has to be moved closer. It’s impossible to take the same images without doing one or the other.

Not true -- you can change the lens focal length on one of the cameras. And in fact to do an appropriate same photograph comparison you'll have to do that. When you take the same photograph with two different sensor size cameras from the same place and at the same f/stop the DOF will be different between them. It will in part be due to the sensor size which will be accounted for in the calculations in the variable circle of confusion.

Joe

But changing focal length to match the field of view will make the DOF thinner. In order for it to be a fair comparison you cannot change focal length.

I’d like to add that *literally nobody here* is arguing that using a longer focal length, or moving a camera closer will not change DOF. Obviously it will.

We are arguing that if you keep all other values the exact same, and change *only the sensor size* the out of focus area of the image will retain the same appearance in both photos. By definition to run this experiment the only thing that can change is the sensor size. Period.

No. I never claimed that and never would. In fact early on in the thread I cautioned that there was no point in making a comparison unless the two cameras/sensors were used to take the same photograph. I'm happy to also claim that if you do as you said and use the same lens from same place at same f/stop with different sensors the DOF is different as I fist demonstrated with the DOF Master illustration, but then it's not the same photo and you have to compare different images with cropping the FX image.

I posted early in the thread and said sensor size effects DOF. It does. Solarflare said that was wrong. He's wrong. You said the effect was indirect. It is not -- it is direct.

If you want to do a comparison that makes any sense then take the same photo with both. Otherwise go ahead and do you FX/DX same lens same place same f/stop but you then must accept the DOF from the full FX image. All the calculators say the DOF will be different. It's stupid to compare DX with FX cropped to DX -- that's the same thing.

Joe

Anything else and you’ve destroyed the experiment.

But it’s the only way

Destin: I sincerely hope that you will be able to try to replicate my 20-foot FX and 34.5 foot DX, full-length portrait example; the definition of the words direct and indirect will become more clear once you see that you can NOT create the same image UNLESS the camera-to-subject distance is altered, materially. There is a direct link, as it relates to creating the same picture, while using same, exact lens, but when also using two, differing format sizes.

You've brought up a point abut depth of field in a final print; that if you do crop the images, you CAN get the same apparent DOF look from two different format cameras. But that is not the normal way to use a camera....there's no sense in shooting on a big, large, high-definition piece of film, and then tossing 40,50,60,70,90 percent of the image captured into the trash, in order to make an 8x10 inch print that approximates the look of a 110-film format capture.

I GET where you are coming from, and yet, and yet earlier, you seemed to indicate that you did not understand that CROPPING THE IMAGE changes the depth of field...so...kind of weird...you've got the concept half right...you have a point.

Anyway...making the SAME PICTURE: try my experiment, please. Do not crop an FX image, but instead, shoot the full-length shot at 34.5 feet on APS-C, then use a full-frame camera from 20 feet away. See whatcha' think!

And, as Ysarex said--it is indeed silly to compare a cropped FX image with a DX-shot image...please try the 20-foot FX versus 34.5 foot APS-C comparison with whatever single focal length lens you havbe at hand (50mm,85mm, or one end of a 70-00 zoom, etc,).

Derrel; that would prove nothing. Obviously moving closer with a full frame camera results in a thinner depth of field. I’ve never once denied that, in fact I was one of the first in this thread to state that fact.

The point of contention however is that many people are claiming that it’s the larger sensor itself causing the thinner DOF; which simply isn’t true. The thinner DOF is simply a side effect of being forced to move closer to replicate the field of View. It’s the change in subject distance causing the thinner DOF in that scenario.

Again, that’s not how scientific experiments work. You can only change *one variable*

If you change nothing other than the size of the sensor, and then adjust the crop of the image to make the comparison fair, you will end up with an identical image.

This is basic 8th grade scientific method stuff guys, and there is really no debating it.

Throwing in a second variable by changing focal length or subject distance completely ruins the accuracy the experiment.

I’ll repeat; If the *only* variable you change at the time of image capture is sensor size, there will be *NO* direct affect on the image whatsoever. In order to gain the thinner DOF sought after by those purchasing full frame cameras, you also have to change other variables in the image capturing process.

Therefore, the sensor size only affects depth of field *indirectly* by forcing you to change other variables to obtain the same field of view.

 

[Ysarex]

Exactly. You're cropping the FX sensor down to DX in the camera. Cropping the FX image after you've taken it does exactly the same thing and produces the same result. The DOF for a DX sensor is the same as the DOF for a DX sensor. If you want to compare the difference in DOF between a DX and FX sensor you have to in fact use the FX sensor uncropped and take the same photo with both cameras.

Joe

But in order to take the same photo with both cameras the image either has to be cropped or the full frame camera has to be moved closer. It’s impossible to take the same images without doing one or the other.

Not true -- you can change the lens focal length on one of the cameras. And in fact to do an appropriate same photograph comparison you'll have to do that. When you take the same photograph with two different sensor size cameras from the same place and at the same f/stop the DOF will be different between them. It will in part be due to the sensor size which will be accounted for in the calculations in the variable circle of confusion.

Joe

But changing focal length to match the field of view will make the DOF thinner. In order for it to be a fair comparison you cannot change focal length.

I’d like to add that *literally nobody here* is arguing that using a longer focal length, or moving a camera closer will not change DOF. Obviously it will.

We are arguing that if you keep all other values the exact same, and change *only the sensor size* the out of focus area of the image will retain the same appearance in both photos. By definition to run this experiment the only thing that can change is the sensor size. Period.

No. I never claimed that and never would. In fact early on in the thread I cautioned that there was no point in making a comparison unless the two cameras/sensors were used to take the same photograph. I'm happy to also claim that if you do as you said and use the same lens from same place at same f/stop with different sensors the DOF is different as I fist demonstrated with the DOF Master illustration, but then it's not the same photo and you have to compare different images with cropping the FX image.

I posted early in the thread and said sensor size effects DOF. It does. Solarflare said that was wrong. He's wrong. You said the effect was indirect. It is not -- it is direct.

If you want to do a comparison that makes any sense then take the same photo with both. Otherwise go ahead and do you FX/DX same lens same place same f/stop but you then must accept the DOF from the full FX image. All the calculators say the DOF will be different. It's stupid to compare DX with FX cropped to DX -- that's the same thing.

Joe

Anything else and you’ve destroyed the experiment.

But it’s the only way

The only logical thing to do is to compare the same photo taken by the two different cameras/sensors.

Destin: I sincerely hope that you will be able to try to replicate my 20-foot FX and 34.5 foot DX, full-length portrait example; the definition of the words direct and indirect will become more clear once you see that you can NOT create the same image UNLESS the camera-to-subject distance is altered, materially. There is a direct link, as it relates to creating the same picture, while using same, exact lens, but when also using two, differing format sizes.

You've brought up a point abut depth of field in a final print; that if you do crop the images, you CAN get the same apparent DOF look from two different format cameras. But that is not the normal way to use a camera....there's no sense in shooting on a big, large, high-definition piece of film, and then tossing 40,50,60,70,90 percent of the image captured into the trash, in order to make an 8x10 inch print that approximates the look of a 110-film format capture.

I GET where you are coming from, and yet, and yet earlier, you seemed to indicate that you did not understand that CROPPING THE IMAGE changes the depth of field...so...kind of weird...you've got the concept half right...you have a point.

Anyway...making the SAME PICTURE: try my experiment, please. Do not crop an FX image, but instead, shoot the full-length shot at 34.5 feet on APS-C, then use a full-frame camera from 20 feet away. See whatcha' think!

And, as Ysarex said--it is indeed silly to compare a cropped FX image with a DX-shot image...please try the 20-foot FX versus 34.5 foot APS-C comparison with whatever single focal length lens you havbe at hand (50mm,85mm, or one end of a 70-00 zoom, etc,).

Derrel; that would prove nothing. Obviously moving closer with a full frame camera results in a thinner depth of field. I’ve never once denied that, in fact I was one of the first in this thread to state that fact.

The point of contention however is that many people are claiming that it’s the larger sensor itself causing the thinner DOF; which simply isn’t true. The thinner DOF is simply a side effect of being forced to move closer to replicate the field of View. It’s the change in subject distance causing the thinner DOF in that scenario.

Again, that’s not how scientific experiments work. You can only change *one variable*

If you change nothing other than the size of the sensor, and then adjust the crop of the image to make the comparison fair, you will end up with an identical image.

NO! That's changing two things. You can't adjust the crop of the image! That's a 2nd variable change. Play by your own rules and in that case you get this:

And you're proven wrong.

This is basic 8th grade scientific method stuff guys, and there is really no debating it.

Throwing in a second variable by changing focal length or subject distance completely ruins the accuracy the experiment.

I’ll repeat; If the *only* variable you change at the time of image capture is sensor size, there will be *NO* direct affect on the image whatsoever.

You're still stuck trying to define DOF as a phenomenon that occurs at the film/sensor rather than in the final image. ONE MORE TIME! DOF is ONLY defined at the final print/display image.

The math says you're wrong. Below in the illustration the only one change is the sensor size. Don Fleming's math isn't wrong.

In order to gain the thinner DOF sought after by those purchasing full frame cameras, you also have to change other variables in the image capturing process.

Therefore, the sensor size only affects depth of field *indirectly* by forcing you to change other variables to obtain the same field of view.

And here again is proof that the sensor size alone has a direct effect:

When comparing the bottom image with the right top image the only change is the sensor size variable: ONLY ONE VARIABLE CHANGE unlike your faulty attempt to change two variables by adding in a crop. Both illustrations prove you're wrong and the bottom one shows how the sensor size change can be isolated from the FL change.

Joe

 

[Destin]

But in order to take the same photo with both cameras the image either has to be cropped or the full frame camera has to be moved closer. It’s impossible to take the same images without doing one or the other.

Not true -- you can change the lens focal length on one of the cameras. And in fact to do an appropriate same photograph comparison you'll have to do that. When you take the same photograph with two different sensor size cameras from the same place and at the same f/stop the DOF will be different between them. It will in part be due to the sensor size which will be accounted for in the calculations in the variable circle of confusion.

Joe

But changing focal length to match the field of view will make the DOF thinner. In order for it to be a fair comparison you cannot change focal length.

I’d like to add that *literally nobody here* is arguing that using a longer focal length, or moving a camera closer will not change DOF. Obviously it will.

We are arguing that if you keep all other values the exact same, and change *only the sensor size* the out of focus area of the image will retain the same appearance in both photos. By definition to run this experiment the only thing that can change is the sensor size. Period.

No. I never claimed that and never would. In fact early on in the thread I cautioned that there was no point in making a comparison unless the two cameras/sensors were used to take the same photograph. I'm happy to also claim that if you do as you said and use the same lens from same place at same f/stop with different sensors the DOF is different as I fist demonstrated with the DOF Master illustration, but then it's not the same photo and you have to compare different images with cropping the FX image.

I posted early in the thread and said sensor size effects DOF. It does. Solarflare said that was wrong. He's wrong. You said the effect was indirect. It is not -- it is direct.

If you want to do a comparison that makes any sense then take the same photo with both. Otherwise go ahead and do you FX/DX same lens same place same f/stop but you then must accept the DOF from the full FX image. All the calculators say the DOF will be different. It's stupid to compare DX with FX cropped to DX -- that's the same thing.

Joe

Anything else and you’ve destroyed the experiment.

But it’s the only way

Destin: I sincerely hope that you will be able to try to replicate my 20-foot FX and 34.5 foot DX, full-length portrait example; the definition of the words direct and indirect will become more clear once you see that you can NOT create the same image UNLESS the camera-to-subject distance is altered, materially. There is a direct link, as it relates to creating the same picture, while using same, exact lens, but when also using two, differing format sizes.

You've brought up a point abut depth of field in a final print; that if you do crop the images, you CAN get the same apparent DOF look from two different format cameras. But that is not the normal way to use a camera....there's no sense in shooting on a big, large, high-definition piece of film, and then tossing 40,50,60,70,90 percent of the image captured into the trash, in order to make an 8x10 inch print that approximates the look of a 110-film format capture.

I GET where you are coming from, and yet, and yet earlier, you seemed to indicate that you did not understand that CROPPING THE IMAGE changes the depth of field...so...kind of weird...you've got the concept half right...you have a point.

Anyway...making the SAME PICTURE: try my experiment, please. Do not crop an FX image, but instead, shoot the full-length shot at 34.5 feet on APS-C, then use a full-frame camera from 20 feet away. See whatcha' think!

And, as Ysarex said--it is indeed silly to compare a cropped FX image with a DX-shot image...please try the 20-foot FX versus 34.5 foot APS-C comparison with whatever single focal length lens you havbe at hand (50mm,85mm, or one end of a 70-00 zoom, etc,).

Derrel; that would prove nothing. Obviously moving closer with a full frame camera results in a thinner depth of field. I’ve never once denied that, in fact I was one of the first in this thread to state that fact.

The point of contention however is that many people are claiming that it’s the larger sensor itself causing the thinner DOF; which simply isn’t true. The thinner DOF is simply a side effect of being forced to move closer to replicate the field of View. It’s the change in subject distance causing the thinner DOF in that scenario.

Again, that’s not how scientific experiments work. You can only change *one variable*

If you change nothing other than the size of the sensor, and then adjust the crop of the image to make the comparison fair, you will end up with an identical image.

NO! That's changing two things. You can't adjust the crop of the image! That's a 2nd variable change. Play by your own rules and in that case you get this:

View attachment 148108

And you're proven wrong.

This is basic 8th grade scientific method stuff guys, and there is really no debating it.

Throwing in a second variable by changing focal length or subject distance completely ruins the accuracy the experiment.

I’ll repeat; If the *only* variable you change at the time of image capture is sensor size, there will be *NO* direct affect on the image whatsoever.

The math says you're wrong. Below in the illustration the only one change is the sensor size. Don Fleming's math isn't wrong.

View attachment 148108

In order to gain the thinner DOF sought after by those purchasing full frame cameras, you also have to change other variables in the image capturing process.

Therefore, the sensor size only affects depth of field *indirectly* by forcing you to change other variables to obtain the same field of view.

And here again is proof that the sensor size alone has a direct effect:

View attachment 148109

When comparing the bottom image with the right top image the only change is the sensor size variable: ONLY ONE VARIABLE CHANGE unlike your faulty attempt to change two variables by adding in a crop. Both illustrations prove you're wrong and the bottom one shows how the sensor size change can be isolated from the FL change.

Joe

But when you change sensor size you change field of view.

So there is literally no way to accurately compare this in an actual experiment, because you’ll always be comparing apples to oranges.

Essential you can do all the math you want, but it will always just be theory because there is no way to do a true comparison.

 

[Ysarex]

Not true -- you can change the lens focal length on one of the cameras. And in fact to do an appropriate same photograph comparison you'll have to do that. When you take the same photograph with two different sensor size cameras from the same place and at the same f/stop the DOF will be different between them. It will in part be due to the sensor size which will be accounted for in the calculations in the variable circle of confusion.

Joe

But changing focal length to match the field of view will make the DOF thinner. In order for it to be a fair comparison you cannot change focal length.

I’d like to add that *literally nobody here* is arguing that using a longer focal length, or moving a camera closer will not change DOF. Obviously it will.

We are arguing that if you keep all other values the exact same, and change *only the sensor size* the out of focus area of the image will retain the same appearance in both photos. By definition to run this experiment the only thing that can change is the sensor size. Period.

No. I never claimed that and never would. In fact early on in the thread I cautioned that there was no point in making a comparison unless the two cameras/sensors were used to take the same photograph. I'm happy to also claim that if you do as you said and use the same lens from same place at same f/stop with different sensors the DOF is different as I fist demonstrated with the DOF Master illustration, but then it's not the same photo and you have to compare different images with cropping the FX image.

I posted early in the thread and said sensor size effects DOF. It does. Solarflare said that was wrong. He's wrong. You said the effect was indirect. It is not -- it is direct.

If you want to do a comparison that makes any sense then take the same photo with both. Otherwise go ahead and do you FX/DX same lens same place same f/stop but you then must accept the DOF from the full FX image. All the calculators say the DOF will be different. It's stupid to compare DX with FX cropped to DX -- that's the same thing.

Joe

Anything else and you’ve destroyed the experiment.

But it’s the only way

Destin: I sincerely hope that you will be able to try to replicate my 20-foot FX and 34.5 foot DX, full-length portrait example; the definition of the words direct and indirect will become more clear once you see that you can NOT create the same image UNLESS the camera-to-subject distance is altered, materially. There is a direct link, as it relates to creating the same picture, while using same, exact lens, but when also using two, differing format sizes.

You've brought up a point abut depth of field in a final print; that if you do crop the images, you CAN get the same apparent DOF look from two different format cameras. But that is not the normal way to use a camera....there's no sense in shooting on a big, large, high-definition piece of film, and then tossing 40,50,60,70,90 percent of the image captured into the trash, in order to make an 8x10 inch print that approximates the look of a 110-film format capture.

I GET where you are coming from, and yet, and yet earlier, you seemed to indicate that you did not understand that CROPPING THE IMAGE changes the depth of field...so...kind of weird...you've got the concept half right...you have a point.

Anyway...making the SAME PICTURE: try my experiment, please. Do not crop an FX image, but instead, shoot the full-length shot at 34.5 feet on APS-C, then use a full-frame camera from 20 feet away. See whatcha' think!

And, as Ysarex said--it is indeed silly to compare a cropped FX image with a DX-shot image...please try the 20-foot FX versus 34.5 foot APS-C comparison with whatever single focal length lens you havbe at hand (50mm,85mm, or one end of a 70-00 zoom, etc,).

Derrel; that would prove nothing. Obviously moving closer with a full frame camera results in a thinner depth of field. I’ve never once denied that, in fact I was one of the first in this thread to state that fact.

The point of contention however is that many people are claiming that it’s the larger sensor itself causing the thinner DOF; which simply isn’t true. The thinner DOF is simply a side effect of being forced to move closer to replicate the field of View. It’s the change in subject distance causing the thinner DOF in that scenario.

Again, that’s not how scientific experiments work. You can only change *one variable*

If you change nothing other than the size of the sensor, and then adjust the crop of the image to make the comparison fair, you will end up with an identical image.

NO! That's changing two things. You can't adjust the crop of the image! That's a 2nd variable change. Play by your own rules and in that case you get this:

View attachment 148108

And you're proven wrong.

This is basic 8th grade scientific method stuff guys, and there is really no debating it.

Throwing in a second variable by changing focal length or subject distance completely ruins the accuracy the experiment.

I’ll repeat; If the *only* variable you change at the time of image capture is sensor size, there will be *NO* direct affect on the image whatsoever.

The math says you're wrong. Below in the illustration the only one change is the sensor size. Don Fleming's math isn't wrong.

View attachment 148108

In order to gain the thinner DOF sought after by those purchasing full frame cameras, you also have to change other variables in the image capturing process.

Therefore, the sensor size only affects depth of field *indirectly* by forcing you to change other variables to obtain the same field of view.

And here again is proof that the sensor size alone has a direct effect:

View attachment 148109

When comparing the bottom image with the right top image the only change is the sensor size variable: ONLY ONE VARIABLE CHANGE unlike your faulty attempt to change two variables by adding in a crop. Both illustrations prove you're wrong and the bottom one shows how the sensor size change can be isolated from the FL change.

Joe

But when you change sensor size you change field of view.

So there is literally no way to accurately compare this in an actual experiment, because you’ll always be comparing apples to oranges.

No. You can do the comparison that makes logical sense. The same one we've done for 100 years before you were born! Take the same photograph with both cameras and compare the results. When you compare the same photo with the same photo you're comparing apples to apples. If managing two variable changes in the equation stresses you're 8th grade education you could try trusting the experts. Or you could get out the math equations for yourself. Or it's really easy to just look at the pictures and see it:

Above is the same photo taken at the same f/stop with two different size sensor cameras. How much of the difference is due to the FL change versus the sensor size? Well we can run the math equations like I did here:

Doing that let's us isolate the FL change over the sensor size change. We can see in the DX camera values that something is causing a change compared with the FX camera. Of course it must be FL. But changing only FL produces the bottom result. Allowing for the sensor size produces the top right result. If the top right result is different than the bottom result then the sensor size must be having a direct effect. Eureka! Sensor size directly effects DOF! Empirically testing these results verifies that the top right result is correct.

Joe

Essential you can do all the math you want, but it will always just be theory because there is no way to do a true comparison.

 

[Designer]

You’re telling me that taking my 50mm 1.8 off of my D500 and putting it onto my D750 is going to magically change the optical formula of the lens?.

No, not of the lens alone, but of the lens-sensor combination working together.

 

[Ysarex]

Here's a little more help:

That's the standard formula for calculating hyperfocal distance which is a basic concept in understanding DOF. Here's a good reference: hyperfocal distance. Where H = hyperfocal distance, f = focal length, N = f/stop value and c = circle of confusion. Not a rocket science formula there.

We need to understand the variable c and how it's value is assigned. Here's a reference: circle of confusion.

And here's a chart with standard values for c when used in DOF calculations.

Note in the above chart that the values for c change relative to the film/sensor size. That's how the size of a sensor or film is accounted for in the math formulas we use to calculate DOF. That's clear proof that sensor/film size is a direct determinant variable. In the math calculations used to determine DOF limits c is a required variable and the value for c changes with sensor/film size. That's proof.

Don't agree? Prove it: Provide references to a DOF calculator and the math formula as proof. So far I'm the only one who has done that.

Joe

 

[Derrel]

Sorry Destin, but you are flat-out off track and in above your head. You need a better understanding of the issue. You just do not understand the issue fully. Your talk about variables misses the issue; you need to compare the SAME PICTURE.

Christ on a bike.

 

[Derrel]

KODAK **invented a new film size and format*** to create deep,deep depth of field with a fixed-focus lens set to about a 3-foot focus distance, and a lens permanently at f/8. The film format Kodak engineers invented was for snapshot shooters, so they could get MORE, or DEEPER, depth of field than the postage-stamp sized 110 cartridge format gave, and more depth of field than the 126 cartridge format provided. Again: Kodak specifically set out to solve an insufficient depth of field problem by making a supremely small, tiny, film format size!!!

The name of the all-new film size and format? Disc. The Kodak Disc camera. Not Disk...but Disc format. A round, cardboard wheel, with teensie-tiny little windows where the film was glued into place, and a revolving film advance system with foolproof loading and advance.

The film size, and the lens length it uses is almost exactly the size that, 40 years later, we have in the Apple iPhone,and other smartphone cameras.

See: the thing is this: a TINY film format uses a short lens length. Short lens lengths arrive at their hyperfocal focusing distance very close to the camera. "Science" and stuff!

See, the engineers at Eastman Kodak understood how depth of field actually works. And they were tired of people complaining that the tiny, APS-C sized or postage-stamp-sized film cameras that used 110 format film were not getting the close-range stuff in-focus, so they invented the world's SMALLEST film format camera at the time...and BOOM! Huuuuuuuge, expansive depth of field, from near to far. Because the tiny format and short lenses give....deeeeep depth of field.

Kind of like snapping focus-free shots with an iPhone...but in the mid-1970's.

Compared to larger-format cameras, smaller format cameras use shorter lenses for every single picture angle of view! Shorter lenses arrive at their point of hyperfocal focusing at CLOSER distances than do longer lenses. The physical ___ size of the film or sensor___

combined with ___the lens lengths needed to achieve specific angles of view___

is, together, what causes different film and sensor format to have different degrees of depth of field.

Again...science and &hi+...

 

[Jamesaz]

Thanks, Derrel. That is interesting information. I'm far from an expert, especially with digital cameras so now I know more. I've always thought of DOF as a volume of space around the plane of focus and really the only 3 dimensional aspect of an otherwise 2 dimensional medium.

 

[Vtec44]

I have nothing to add and just want to post pretty pictures

One is from my Nikon D800 with a 85 f1.4 and one is from my Pentax 645Nii with a 75mm f2.8

 

[limr]

KODAK **invented a new film size and format*** to create deep,deep depth of field with a fixed-focus lens set to about a 3-foot focus distance, and a lens permanently at f/8. The film format Kodak engineers invented was for snapshot shooters, so they could get MORE, or DEEPER, depth of field than the postage-stamp sized 110 cartridge format gave, and more depth of field than the 126 cartridge format provided. Again: Kodak specifically set out to solve an insufficient depth of field problem by making a supremely small, tiny, film format size!!!

The name of the all-new film size and format? Disc. The Kodak Disc camera. Not Disk...but Disc format. A round, cardboard wheel, with teensie-tiny little windows where the film was glued into place, and a revolving film advance system with foolproof loading and advance.

The film size, and the lens length it uses is almost exactly the size that, 40 years later, we have in the Apple iPhone,and other smartphone cameras.

See: the thing is this: a TINY film format uses a short lens length. Short lens lengths arrive at their hyperfocal focusing distance very close to the camera. "Science" and stuff!

See, the engineers at Eastman Kodak understood how depth of field actually works. And they were tired of people complaining that the tiny, APS-C sized or postage-stamp-sized film cameras that used 110 format film were not getting the close-range stuff in-focus, so they invented the world's SMALLEST film format camera at the time...and BOOM! Huuuuuuuge, expansive depth of field, from near to far. Because the tiny format and short lenses give....deeeeep depth of field.

Kind of like snapping focus-free shots with an iPhone...but in the mid-1970's.

Compared to larger-format cameras, smaller format cameras use shorter lenses for every single picture angle of view! Shorter lenses arrive at their point of hyperfocal focusing at CLOSER distances than do longer lenses. The physical ___ size of the film or sensor___

combined with ___the lens lengths needed to achieve specific angles of view___

is, together, what causes different film and sensor format to have different degrees of depth of field.

Again...science and &hi+...

Holy cow, the disc cameras! Forgot all about those. My sister, the gadget queen, had one. I remember being...unimpressed.

 

[Designer]

Thanks, Derrel. That is interesting information. I'm far from an expert, especially with digital cameras so now I know more. I've always thought of DOF as a volume of space around the plane of focus and really the only 3 dimensional aspect of an otherwise 2 dimensional medium.

For you and the original poster, lenses render differently, some making 2-dimensional images look flat (2-dimensional) and some will render with more depth, creating the impression of looking at a 3-dimensional image. Not precisely, of course, but there is a range of this ability, with some lenses being outstanding and some maybe not so much.