DOF with FFs and APS-C

normhead · 10-23-2013, 12:11 PM

Originally posted by John Poirier

Frankly, I'm appalled at your methods. Taking pictures and relying on your own judgement to decide what works for you? Shocking!

Other than that, my own observations coincide with yours. APS-C offers some advantages in terms of depth of field for a given field of view, if you want lots of DOF- which is important to me as a landscape photographer. On the other hand, at the moment FF offers higher resolution which is important to me as a landscape photographer who makes large prints.

I'm not going to get too complicated about the tradeoffs involved in increased DOF and apparent sharpness vs diffraction effects and viewing distance. I do know that by closing down a stop or two on full frame I can come close to the DOF of APS-C, and have a bigger file to boot. From experience, I know that with 3-dimensional subjects gains in apparent sharpness with increased DOF generally outweigh diffraction effects. I usually work on a tripod, so shutter speeds don't matter much.

I did a lot of FF DSLR work before retiring from my old job, so I'm quite confident about what tradeoffs I want to make for my own purposes.

I work quite happily with APS-C, but ultimately will move to full frame for larger prints. I'm sure you are able to make very good large prints from APS-C files. I know I can. However, I would like to take quality up another notch.

What it really comes down to is different horses for different courses.

Exactly... and for landscape, I'd really like a K-02 FF that I could put a tilt shift lens on... and I'd carry it just for when I needed it. And who knows, if things stay as they are and I don't get what I want, maybe Sony A7r with a couple Samyangs will be the thing for landscape. MY biggest problem with FF is how big they are. Not that there's something wrong with the images, especially for landscape. However I did get to compare some landscape images taken side by side with a D800 owner this summer, and the results were inconclusive in terms of which images I like better, even at 1:1 resolutions. So it would take some really serious testing to move me to a full frame, unless I were doing prints above 24x36. So far my largest prints are 20-30, so I've got room to grow. And I'm guessing my K-3 will happily take me up to 26x40.

Andi Lo · 10-23-2013, 12:44 PM

Normhead's method is the best I think

Just try it out yourself and see the DOF difference.

stevebrot · 10-23-2013, 01:10 PM

Originally posted by Andi Lo

DOF as today's viewfinder is unable to show the effects of aperture wider than 2.8.

With the stock Pentax focus screen, it is closer to f/4. No wonder people have trouble doing critical focus with vintage fast glass.

Steve

stevebrot · 10-23-2013, 01:15 PM

Originally posted by Rondec

There is one stop less depth of field with full frame than with APS-C.

Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed).

There, I have said it...end of rant.

Steve

stevebrot · 10-23-2013, 01:19 PM

Originally posted by Rondec

I do think the pursuit of narrow depth of field has gotten a little silly

Agreed. Having worked with larger formats (up to 4x5), I can tell you without reserve that more DOF is generally better than less.

The one huge exception is with environmental portraits. Images with strongly OOF backgrounds are highly desirable and marketable and are one of the hallmarks of medium format portraiture. Those are hard enough to do with 35mm and almost impossible with APS-C.

Steve

tuco · 10-23-2013, 02:15 PM

Originally posted by Rondec

...
I do think the pursuit of narrow depth of field has gotten a little silly and I am bothered, frankly, by portraits in which half of a person's features are out of focus or soft. But each to their own...

Today we can apply all kinds of skin smoothing in the image editor. In the old days, especially with LF, shallow DOF was a method to help smooth out skin features by leaving mostly the eyes in focus. Sure, shallow DOF like this does not appeal to everyone's taste but thank goodness we have choices.

carrrlangas · 10-23-2013, 02:17 PM

Lost of information here. To throw some more into the mix:
Viewfinders play a part when reviewing the depth of field through it. They can be designed to render DoF accurately at bigger apertures (ie f/1.4) as it was in most manual focus film cameras or to stay bright when using slower lenses (ie f/4-5.6) as in modern SLRs. I think the viewfinder on the K-5 can´t render DoF accurately for apertures smaller than f/2.8 (not sure about focal lengths and focal distance but probably 50mm - 1m as it is the standard?)
Luckily, Liveview can render DoF accurately....

**Rondec** · 10-23-2013, 02:41 PM

Originally posted by stevebrot

Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed).

There, I have said it...end of rant.

Steve

When I use stop here, I mean the difference in depth of field between f2.8 and f4 and f5.6. That's all. Since there is a one to one relationship between iso/aperture/shutter speed it works out.

tuco · 10-23-2013, 03:05 PM

I occasionally shoot a landscape on my Pentax 6x7. And when your normal lens choices are either 90mm or 105mm, I don't have sympathy for someone saying small format is hard to get DOF.

Andi Lo · 10-23-2013, 04:25 PM

Originally posted by stevebrot

Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed).

There, I have said it...end of rant.

Steve

Yes, I'm guilty of this and I agree that it's not correct, however I dont think there's a good term for it. How do you quantify how blurred an image is anyway?

I dont think distance plane of focus would be accurate as it differs with different FL.

normhead · 10-23-2013, 04:58 PM

Originally posted by Andi Lo

Yes, I'm guilty of this and I agree that it's not correct, however I dont think there's a good term for it. How do you quantify how blurred an image is anyway?

I dont think distance plane of focus would be accurate as it differs with different FL.

DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF differently at different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept.

You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate.

As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy.

Andi Lo · 10-23-2013, 05:27 PM

Originally posted by normhead

DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF at different different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept.

You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate.

As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy.

You're right, I should stop referring to it by that and just say it's less DOF and more blurry

**Rondec** · 10-23-2013, 06:14 PM

Originally posted by normhead

DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF at different different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept.

You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate.

As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy.

You are right of course, but it would be nice to have some term that indicates the change that you get in depth of field (for a static distance) when you change the aperture one stop. I'm not good with coining words, or I would come up with one on the spot for you.

normhead · 10-23-2013, 06:36 PM

Quote:

You're right, I should stop referring to it by that and just say it's less DOF and more blurry

Eeee Gad!!!! Why didn't I think of that?

wombat2go · 10-23-2013, 07:13 PM

I found the stop down DOF previews on the slr/dslr s to be of not much use simply because the image is too small.

I have some cameras with no slr or rangefinder so I made a spreadsheet to get predictions based on the near and far limit functions.
The core issue is the size of the final image.
i use a 22 inch Eizo with about 1500 vertical pixels, so the COC is based on that.

I cloned spreadsheets for some lenses and adjusted FL, sensor size and aperture etc, just to get a handle on it.

M4/3, Pentax-110 18 mm at f/5.6
at 5 meter,Predicted allowable focus error of plus or minus 20%.

Easy! Here the scale focus was at 3 metre, somewhere in the midst of the 2 young ladies and the pro, none of whom probably care about DOF at all.
The pro photographer was quite genial and offered to take some family shots with the humble M43 and the tiny manual P-110,
but I was too ashamed to give it to him, after his big brand new Nikon! And he did take some excellent shots of us with that Nikon.
https://app.box.com/s/42j9ocuem9jmrqo4uvsr

Pentax 6 x 7 , Tak 90 mm at f/11 on the Graflex
at 5 meter, Predicted allowable focus error of plus or minus 14%.

Need to estimate a bit better, but still mostly OK! ( posted before I think)
https://app.box.com/s/pzzorays1lydomsk9rre

Of course, as the distance gets longer the estimation gets easier. As Norm mentioned, the close up guys can't do such approximations.

10-23-2013, 04:58 PM	#26
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by Andi Lo Yes, I'm guilty of this and I agree that it's not correct, however I dont think there's a good term for it. How do you quantify how blurred an image is anyway? I dont think distance plane of focus would be accurate as it differs with different FL. DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF differently at different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept. You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate. As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy. Last edited by normhead; 10-23-2013 at 06:18 PM.

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10-23-2013, 12:11 PM	#16
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by John Poirier Frankly, I'm appalled at your methods. Taking pictures and relying on your own judgement to decide what works for you? Shocking! Other than that, my own observations coincide with yours. APS-C offers some advantages in terms of depth of field for a given field of view, if you want lots of DOF- which is important to me as a landscape photographer. On the other hand, at the moment FF offers higher resolution which is important to me as a landscape photographer who makes large prints. I'm not going to get too complicated about the tradeoffs involved in increased DOF and apparent sharpness vs diffraction effects and viewing distance. I do know that by closing down a stop or two on full frame I can come close to the DOF of APS-C, and have a bigger file to boot. From experience, I know that with 3-dimensional subjects gains in apparent sharpness with increased DOF generally outweigh diffraction effects. I usually work on a tripod, so shutter speeds don't matter much. I did a lot of FF DSLR work before retiring from my old job, so I'm quite confident about what tradeoffs I want to make for my own purposes. I work quite happily with APS-C, but ultimately will move to full frame for larger prints. I'm sure you are able to make very good large prints from APS-C files. I know I can. However, I would like to take quality up another notch. What it really comes down to is different horses for different courses. Exactly... and for landscape, I'd really like a K-02 FF that I could put a tilt shift lens on... and I'd carry it just for when I needed it. And who knows, if things stay as they are and I don't get what I want, maybe Sony A7r with a couple Samyangs will be the thing for landscape. MY biggest problem with FF is how big they are. Not that there's something wrong with the images, especially for landscape. However I did get to compare some landscape images taken side by side with a D800 owner this summer, and the results were inconclusive in terms of which images I like better, even at 1:1 resolutions. So it would take some really serious testing to move me to a full frame, unless I were doing prints above 24x36. So far my largest prints are 20-30, so I've got room to grow. And I'm guessing my K-3 will happily take me up to 26x40.

10-23-2013, 12:44 PM	#17
Andi Lo Veteran Member Join Date: Jul 2008 Location: Halifax, Nova Scotia Posts: 2,924	Normhead's method is the best I think Just try it out yourself and see the DOF difference.

10-23-2013, 01:10 PM	#18
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Andi Lo DOF as today's viewfinder is unable to show the effects of aperture wider than 2.8. With the stock Pentax focus screen, it is closer to f/4. No wonder people have trouble doing critical focus with vintage fast glass. Steve

10-23-2013, 01:15 PM	#19
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Rondec There is one stop less depth of field with full frame than with APS-C. Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed). There, I have said it...end of rant. Steve

10-23-2013, 01:19 PM	#20
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Rondec I do think the pursuit of narrow depth of field has gotten a little silly Agreed. Having worked with larger formats (up to 4x5), I can tell you without reserve that more DOF is generally better than less. The one huge exception is with environmental portraits. Images with strongly OOF backgrounds are highly desirable and marketable and are one of the hallmarks of medium format portraiture. Those are hard enough to do with 35mm and almost impossible with APS-C. Steve

10-23-2013, 02:15 PM	#21
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,026	Originally posted by Rondec ... I do think the pursuit of narrow depth of field has gotten a little silly and I am bothered, frankly, by portraits in which half of a person's features are out of focus or soft. But each to their own... Today we can apply all kinds of skin smoothing in the image editor. In the old days, especially with LF, shallow DOF was a method to help smooth out skin features by leaving mostly the eyes in focus. Sure, shallow DOF like this does not appeal to everyone's taste but thank goodness we have choices.

10-23-2013, 02:17 PM	#22
carrrlangas Veteran Member Join Date: Mar 2012 Location: Joensuu (Finland) Photos: Gallery Posts: 1,761	Lost of information here. To throw some more into the mix: Viewfinders play a part when reviewing the depth of field through it. They can be designed to render DoF accurately at bigger apertures (ie f/1.4) as it was in most manual focus film cameras or to stay bright when using slower lenses (ie f/4-5.6) as in modern SLRs. I think the viewfinder on the K-5 can´t render DoF accurately for apertures smaller than f/2.8 (not sure about focal lengths and focal distance but probably 50mm - 1m as it is the standard?) Luckily, Liveview can render DoF accurately....

10-23-2013, 02:41 PM	#23
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	Originally posted by stevebrot Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed). There, I have said it...end of rant. Steve When I use stop here, I mean the difference in depth of field between f2.8 and f4 and f5.6. That's all. Since there is a one to one relationship between iso/aperture/shutter speed it works out.

10-23-2013, 03:05 PM	#24
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,026	I occasionally shoot a landscape on my Pentax 6x7. And when your normal lens choices are either 90mm or 105mm, I don't have sympathy for someone saying small format is hard to get DOF.

10-23-2013, 04:25 PM	#25
Andi Lo Veteran Member Join Date: Jul 2008 Location: Halifax, Nova Scotia Posts: 2,924	Originally posted by stevebrot Pet peeve of mine, but I hate it when people use the word "stop" to refer to DOF. It truly has no meaning in this context and I am not even sure that statements like the above reliably true. DOF is expressed in units of linear measurement while "stop" is expressed in exposure terms (relative aperture or shutter speed). There, I have said it...end of rant. Steve Yes, I'm guilty of this and I agree that it's not correct, however I dont think there's a good term for it. How do you quantify how blurred an image is anyway? I dont think distance plane of focus would be accurate as it differs with different FL.

10-23-2013, 05:27 PM	#27
Andi Lo Veteran Member Join Date: Jul 2008 Location: Halifax, Nova Scotia Posts: 2,924	Originally posted by normhead DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF at different different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept. You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate. As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy. You're right, I should stop referring to it by that and just say it's less DOF and more blurry

10-23-2013, 06:14 PM	#28
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	Originally posted by normhead DoF is a distance... the distance between the nearest and furthest point in acceptable focus. IN my test, my 35 2.4 at about 8 inches from the subject gave me about 12 mm DoF. Calling it a stop is crazy. For one thing, as the focal plane gets further from the film plane, DoF increases. That has nothing to do with an F-stop. How a lens is made, how much corrected, whether it's internal or external focusing also affects DoF at different different distances from the film plane. The idea of defining DoF in terms of stops is just incredibly sloppy. Not helped by the fact that some people who know better are in love with the concept. You could define with a table of measurements how much DoF changed with one stop of aperture. But you'd have to do it with every lens, for every distance from it's closest focus to infinity, and it wouldn't be universal. Again, people who should know better are pretending these are simple lenses. An assumption that is frequently used for rudimentary estimates, but which is in no way to be considered either precise or accurate. As I said, I find it sad that people who should know better use such an obvious misrepresentation, creating unnecessary confusion by deliberately appropriating a term with it's own meaning to describe something so wishy washy. You are right of course, but it would be nice to have some term that indicates the change that you get in depth of field (for a static distance) when you change the aperture one stop. I'm not good with coining words, or I would come up with one on the spot for you.

10-23-2013, 06:36 PM	#29
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Quote: You're right, I should stop referring to it by that and just say it's less DOF and more blurry Eeee Gad!!!! Why didn't I think of that?

10-23-2013, 07:13 PM	#30
wombat2go Veteran Member Join Date: Jan 2010 Location: Michigan Photos: Gallery Posts: 2,207	I found the stop down DOF previews on the slr/dslr s to be of not much use simply because the image is too small. I have some cameras with no slr or rangefinder so I made a spreadsheet to get predictions based on the near and far limit functions. The core issue is the size of the final image. i use a 22 inch Eizo with about 1500 vertical pixels, so the COC is based on that. I cloned spreadsheets for some lenses and adjusted FL, sensor size and aperture etc, just to get a handle on it. M4/3, Pentax-110 18 mm at f/5.6 at 5 meter,Predicted allowable focus error of plus or minus 20%. Easy! Here the scale focus was at 3 metre, somewhere in the midst of the 2 young ladies and the pro, none of whom probably care about DOF at all. The pro photographer was quite genial and offered to take some family shots with the humble M43 and the tiny manual P-110, but I was too ashamed to give it to him, after his big brand new Nikon! And he did take some excellent shots of us with that Nikon. https://app.box.com/s/42j9ocuem9jmrqo4uvsr Pentax 6 x 7 , Tak 90 mm at f/11 on the Graflex at 5 meter, Predicted allowable focus error of plus or minus 14%. Need to estimate a bit better, but still mostly OK! ( posted before I think) https://app.box.com/s/pzzorays1lydomsk9rre Of course, as the distance gets longer the estimation gets easier. As Norm mentioned, the close up guys can't do such approximations.