DOF with FFs and APS-C

stevebrot · 10-26-2013, 10:14 AM

Originally posted by tuco

I know, just say 2 more or less stops of bokeh. That seems to play right into many people's misunderstanding of what bokeh is.

ROFL

Steve

stevebrot · 10-26-2013, 10:21 AM

Originally posted by ElJamoquio

Mrs. ElJamoquio was taking pics with her new Ricoh APS-C and about cried when she saw the same pics from the D600. I actually didn't think they were THAT different.

That is sort of how I felt when Tuco started posting his D600 stuff on Flickr.

Steve

stevebrot · 10-26-2013, 10:30 AM

Originally posted by BrianR

No more subjective than the rest of the DoF equations. Namely pick an acceptable circle of confusion depending on print size, viewing distance, and how drunk the viewer is and go from there.

Sad, but so true. I have taken part in some extensive and very technical threads on this site regarding DOF and when all the research is done, your statement is the final conclusion. The calculated DOF is truly based on several arbitrary assumptions:

Acceptable blur
Final image size
Viewing distance for final image

Needless to say, in this world of pixel peeping with the speed of a mouse click, acceptable blur has taken on a completely different meaning. To be completely honest, I tell people that there is truly only one true point of focus, regardless of aperture. Anything in front of or behind that point will be less sharp. How much so is dependent on aperture, final image size, and viewing distance.

Steve

carrrlangas · 10-26-2013, 10:50 AM

Originally posted by stevebrot

Sad, but so true. I have taken part in some extensive and very technical threads on this site regarding DOF and when all the research is done, your statement is the final conclusion. The calculated DOF is truly based on several arbitrary assumptions:
Acceptable blur
Final image size
Viewing distance for final image
Needless to say, in this world of pixel peeping with the speed of a mouse click, acceptable blur has taken on a completely different meaning. To be completely honest, I tell people that there is truly only one true point of focus, regardless of aperture. Anything in front of or behind that point will be less sharp. How much so is dependent on aperture, final image size, and viewing distance.

Steve

Steve or others, would you know about some good biblography to extand on this subject? I am putting together a small presentation for some friends and their friends with technical bits I´ve been collecting (a lot from this forum!) and they are curious the learn about them.

wombat2go · 10-26-2013, 12:00 PM

Originally posted by carrrlangas

some good biblography

Herbert Keppler "The Pentax Way" He refers to DOF in a practical way throughout the book with simple diagrams. However, only for the 35mm film format

Arthur Cox " Photographic Optics" Pages 64 to 97. He shows the math with descriptions, geometric optics and lens diagrams. That book is pre- computer, however I use his functions in a spreadsheet.

A very simple but usable computer aided design application is "OpticalRayTracer.jar" it is GPL, free and runs on Java, so it is platform agnostic.
Here it is modeling a vintage 90mm wide angle lens at f/11 on a 4 x 5 film plane.
I can model that because the prescription is available, However I don't think the prescriptions for modern lenses are available in public domain?
The app models dispersion as well for lateral chromatic abberation, and it is possible to change things (for example the aperture), zoom into the film plane and see the circle of confusion.

tuco · 10-26-2013, 12:10 PM

Originally posted by stevebrot

That is sort of how I felt when Tuco started posting his D600 stuff on Flickr.
Steve

The biggest wow-factor I experienced when I first got that camera coming from a K-7 and XP1 is something nobody here seems to really care about and that's fine. That camera was traded in for a D800 btw.

It seems everyone's arguments center around size, sharpness and DOF when it comes to brand-X crop sensor vs brand-Y FF. All valid arguments. But when I prioritized my list of things I wanted in my next digital camera those mentioned attributes were near the bottom of my short priority list.

I shoot my film cameras when I want to do things on the methodical and manual side. When I hold a fancy modern camera, I expect a way more from it. Ricoh is only starting to move the Pentax brand in the direction with attributes that were high on my priority list.

traderdrew · 10-26-2013, 02:46 PM

Originally posted by carrrlangas

Steve or others, would you know about some good biblography to extand on this subject? I am putting together a small presentation for some friends and their friends with technical bits I´ve been collecting (a lot from this forum!) and they are curious the learn about them.

I don't know of any sources on this. Without knowing exactly what field of view is, I think it is worth mentioning that field of view (maybe we can call it FOV) can be viewed in two or three dimensions to help understand it.

I view noise as affected by the field of view of FFs and APS-C cameras also.

normhead · 10-26-2013, 02:50 PM - **1 Like**

You might want to have a look at this.... it will tell you everything you need to know.

Pentax Wins....

Andi Lo · 10-28-2013, 07:25 AM

Originally posted by normhead

You might want to have a look at this.... it will tell you everything you need to know.

Pentax Wins....

Doesnt matter, got FF

(the above is a meme joke by the way), I'm glad that K-3 is getting good reviews, it can only bode well for the future of Pentax.

normhead · 10-28-2013, 07:41 AM

Originally posted by Andi Lo

Doesnt matter, got FF

(the above is a meme joke by the way), I'm glad that K-3 is getting good reviews, it can only bode well for the future of Pentax.

It occurs to me is that there is so much anti-Pentax BS posted on this forum, after a while even I start to believe it. It's just a relief to see someone saying nice things about Pentax, even if they are a bunch of bozos.

stevebrot · 10-28-2013, 08:48 AM

Originally posted by tuco

The biggest wow-factor I experienced when I first got that camera coming from a K-7 and XP1 is something nobody here seems to really care about and that's fine.

Let me guess...AF speed and accuracy

Steve

(BTW...congrats on the D800...Major envy from this corner of the world...)

jsherman999 · 10-28-2013, 11:06 AM

Originally posted by BrianR

Keeping the field of view or the framing of the subject the same is a sensible way to compare the formats, and is the one people usually have in mind when they make the claim "FF has shallower DoF than crop" so I think it's usually worth mentioning. However, I don't really care what parameters are changed when comparing the DoF as long as they're explicitly stated. I've lost count of the disagreements I've seen between two people who were both right but failed to clearly indicate what exactly they were comparing and thus seemed to have reached different conclusions when all they had done was answer different questions.

Change focal length, distance, aperture, format, print size, or don't, it doesn't matter but being clear about it cuts confusion by at least one stop. Maybe two.

If only there were some way to establish a relationship between formats, like some sort of equivalence concept...

Seriously though, this is spot-on, and it pertains to other things like 'perspective'. I've been in page-long discussions going no-where before I realized the other folks were using a different definition of a term or terms, and neither of us were wrong in what we were arguing, we were just arguing about different things using the same terms.

.

normhead · 10-28-2013, 11:39 AM

Originally posted by jsherman999

If only there were some way to establish a relationship between formats, like some sort of equivalence concept...

Seriously though, this is spot-on, and it pertains to other things like 'perspective'. I've been in page-long discussions going no-where before I realized the other folks were using a different definition of a term or terms, and neither of us were wrong in what we were arguing, we were just arguing about different things using the same terms.

.

I've never done that.

Ikarus · 10-28-2013, 06:10 PM

Originally posted by normhead

You might want to have a look at this.... it will tell you everything you need to know.

Pentax Wins....

Great job by the K-3 and the 55mm f/1.4! That said, it is very apparent from the example pictures that the DOF of the Nikon is much shallower at the same aperture. I wouldn't go as far as to invoke apples and oranges, but the comparison would be a lot more meaningful had the author at least attempted to normalize for DOF, even though that's not possible without error, since the aperture can only be adjusted in discrete steps.

ElJamoquio · 10-28-2013, 08:20 PM

You could get close in aperture, certainly within a third of a stop. Even with discrete control, though, it's tough because the rated aperture and the actual aperture can deviate.

Certainly I would have produced nominally the same picture, same focus point, and same exposure before I would have posted results on the web.

Nevertheless the K-3 results looked fine.

10-26-2013, 10:30 AM	#93
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by BrianR No more subjective than the rest of the DoF equations. Namely pick an acceptable circle of confusion depending on print size, viewing distance, and how drunk the viewer is and go from there. Sad, but so true. I have taken part in some extensive and very technical threads on this site regarding DOF and when all the research is done, your statement is the final conclusion. The calculated DOF is truly based on several arbitrary assumptions: Acceptable blur Final image size Viewing distance for final image Needless to say, in this world of pixel peeping with the speed of a mouse click, acceptable blur has taken on a completely different meaning. To be completely honest, I tell people that there is truly only one true point of focus, regardless of aperture. Anything in front of or behind that point will be less sharp. How much so is dependent on aperture, final image size, and viewing distance. Steve

10-26-2013, 12:00 PM	#95
wombat2go Veteran Member Join Date: Jan 2010 Location: Michigan Photos: Gallery Posts: 2,207	Originally posted by carrrlangas some good biblography Herbert Keppler "The Pentax Way" He refers to DOF in a practical way throughout the book with simple diagrams. However, only for the 35mm film format Arthur Cox " Photographic Optics" Pages 64 to 97. He shows the math with descriptions, geometric optics and lens diagrams. That book is pre- computer, however I use his functions in a spreadsheet. A very simple but usable computer aided design application is "OpticalRayTracer.jar" it is GPL, free and runs on Java, so it is platform agnostic. Here it is modeling a vintage 90mm wide angle lens at f/11 on a 4 x 5 film plane. I can model that because the prescription is available, However I don't think the prescriptions for modern lenses are available in public domain? The app models dispersion as well for lateral chromatic abberation, and it is possible to change things (for example the aperture), zoom into the film plane and see the circle of confusion. Attached Images

10-28-2013, 11:06 AM	#102
jsherman999 Veteran Member Join Date: Dec 2007 Photos: Gallery Posts: 8,237	well seen Originally posted by BrianR Keeping the field of view or the framing of the subject the same is a sensible way to compare the formats, and is the one people usually have in mind when they make the claim "FF has shallower DoF than crop" so I think it's usually worth mentioning. However, I don't really care what parameters are changed when comparing the DoF as long as they're explicitly stated. I've lost count of the disagreements I've seen between two people who were both right but failed to clearly indicate what exactly they were comparing and thus seemed to have reached different conclusions when all they had done was answer different questions. Change focal length, distance, aperture, format, print size, or don't, it doesn't matter but being clear about it cuts confusion by at least one stop. Maybe two. If only there were some way to establish a relationship between formats, like some sort of equivalence concept... Seriously though, this is spot-on, and it pertains to other things like 'perspective'. I've been in page-long discussions going no-where before I realized the other folks were using a different definition of a term or terms, and neither of us were wrong in what we were arguing, we were just arguing about different things using the same terms. .

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10-26-2013, 10:14 AM	#91
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by tuco I know, just say 2 more or less stops of bokeh. That seems to play right into many people's misunderstanding of what bokeh is. ROFL Steve

10-26-2013, 10:21 AM	#92
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by ElJamoquio Mrs. ElJamoquio was taking pics with her new Ricoh APS-C and about cried when she saw the same pics from the D600. I actually didn't think they were THAT different. That is sort of how I felt when Tuco started posting his D600 stuff on Flickr. Steve

10-26-2013, 10:50 AM	#94
carrrlangas Veteran Member Join Date: Mar 2012 Location: Joensuu (Finland) Photos: Gallery Posts: 1,761	Originally posted by stevebrot Sad, but so true. I have taken part in some extensive and very technical threads on this site regarding DOF and when all the research is done, your statement is the final conclusion. The calculated DOF is truly based on several arbitrary assumptions: Acceptable blur Final image size Viewing distance for final image Needless to say, in this world of pixel peeping with the speed of a mouse click, acceptable blur has taken on a completely different meaning. To be completely honest, I tell people that there is truly only one true point of focus, regardless of aperture. Anything in front of or behind that point will be less sharp. How much so is dependent on aperture, final image size, and viewing distance. Steve Steve or others, would you know about some good biblography to extand on this subject? I am putting together a small presentation for some friends and their friends with technical bits I´ve been collecting (a lot from this forum!) and they are curious the learn about them.

10-26-2013, 12:10 PM	#96
tuco Pentaxian Join Date: Jul 2009 Location: Pugetopolis Posts: 11,025	Originally posted by stevebrot That is sort of how I felt when Tuco started posting his D600 stuff on Flickr. Steve The biggest wow-factor I experienced when I first got that camera coming from a K-7 and XP1 is something nobody here seems to really care about and that's fine. That camera was traded in for a D800 btw. It seems everyone's arguments center around size, sharpness and DOF when it comes to brand-X crop sensor vs brand-Y FF. All valid arguments. But when I prioritized my list of things I wanted in my next digital camera those mentioned attributes were near the bottom of my short priority list. I shoot my film cameras when I want to do things on the methodical and manual side. When I hold a fancy modern camera, I expect a way more from it. Ricoh is only starting to move the Pentax brand in the direction with attributes that were high on my priority list.

10-26-2013, 02:46 PM	#97
traderdrew Veteran Member Join Date: Jun 2010 Location: Florida Photos: Gallery \| Albums Posts: 639 Original Poster	Originally posted by carrrlangas Steve or others, would you know about some good biblography to extand on this subject? I am putting together a small presentation for some friends and their friends with technical bits I´ve been collecting (a lot from this forum!) and they are curious the learn about them. I don't know of any sources on this. Without knowing exactly what field of view is, I think it is worth mentioning that field of view (maybe we can call it FOV) can be viewed in two or three dimensions to help understand it. I view noise as affected by the field of view of FFs and APS-C cameras also.

10-26-2013, 02:50 PM - 1 Like	#98
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	You might want to have a look at this.... it will tell you everything you need to know. Pentax Wins....

10-28-2013, 07:25 AM	#99
Andi Lo Veteran Member Join Date: Jul 2008 Location: Halifax, Nova Scotia Posts: 2,924	Originally posted by normhead You might want to have a look at this.... it will tell you everything you need to know. Pentax Wins.... Doesnt matter, got FF (the above is a meme joke by the way), I'm glad that K-3 is getting good reviews, it can only bode well for the future of Pentax.

10-28-2013, 07:41 AM	#100
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by Andi Lo Doesnt matter, got FF (the above is a meme joke by the way), I'm glad that K-3 is getting good reviews, it can only bode well for the future of Pentax. It occurs to me is that there is so much anti-Pentax BS posted on this forum, after a while even I start to believe it. It's just a relief to see someone saying nice things about Pentax, even if they are a bunch of bozos.

10-28-2013, 08:48 AM	#101
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by tuco The biggest wow-factor I experienced when I first got that camera coming from a K-7 and XP1 is something nobody here seems to really care about and that's fine. Let me guess...AF speed and accuracy Steve (BTW...congrats on the D800...Major envy from this corner of the world...)

10-28-2013, 11:39 AM	#103
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by jsherman999 If only there were some way to establish a relationship between formats, like some sort of equivalence concept... Seriously though, this is spot-on, and it pertains to other things like 'perspective'. I've been in page-long discussions going no-where before I realized the other folks were using a different definition of a term or terms, and neither of us were wrong in what we were arguing, we were just arguing about different things using the same terms. . I've never done that.

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10-28-2013, 06:10 PM	#104
Ikarus Veteran Member Join Date: Apr 2010 Location: California Photos: Albums Posts: 484	Originally posted by normhead You might want to have a look at this.... it will tell you everything you need to know. Pentax Wins.... Great job by the K-3 and the 55mm f/1.4! That said, it is very apparent from the example pictures that the DOF of the Nikon is much shallower at the same aperture. I wouldn't go as far as to invoke apples and oranges, but the comparison would be a lot more meaningful had the author at least attempted to normalize for DOF, even though that's not possible without error, since the aperture can only be adjusted in discrete steps.

10-28-2013, 08:20 PM	#105
ElJamoquio Veteran Member Join Date: Feb 2011 Posts: 4,873	You could get close in aperture, certainly within a third of a stop. Even with discrete control, though, it's tough because the rated aperture and the actual aperture can deviate. Certainly I would have produced nominally the same picture, same focus point, and same exposure before I would have posted results on the web. Nevertheless the K-3 results looked fine.