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03-23-2016, 07:20 AM   #61
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Diffraction is a non-issue except for pixelpeeping. There are tons of fine art prints on peoples walls shot well into diffraction. Many of my 645 images are shot at F:22 or 32, and although this can be seen under a high magnification loupe (this is film), in the final print no one can tell. Just apply a tad more sharpening....

---------- Post added 03-23-16 at 03:27 PM ----------

QuoteOriginally posted by osv Quote
no, with bigger sensors you get more control over dof, because there can be more usable aperture stops on the lens.

i'll repeat the obvious yet again... if i want to shoot at the edge of visible diffraction, it's ~f/8 on crop and ~f/11 on ff, so i can't even use f/11 on crop.

that is real-world applicability... there is no loss of dof anywhere with ff, unless perhaps you want to ruin pq with an f/32 aperture stop, and your lens doesn't have that stop.

I have much more control over DOF with my K3 than my 645NII. This is based on real life experience. In fact, there are images and cant get with the 645 which are easy to achieve with the K3.

03-23-2016, 07:37 AM   #62
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OK someone help me here.... does diffraction become less noticeable of larger formats?

I was under the impressions that diffraction became less noticeable in larger formats, and that diffraction would have more effect on a smaller sensor. Was that incorrect?

I know Ansel Adams and others shot landscapes at ƒ64 and that that would be unthinkable on a K-3, I know my full frame 8 inch by 10 inch cameras achieved narrow DoF wide open at ƒ5.6. I Just assumed there was a sliding scale there.

How do you compare K-3 and 645 diffraction without noting that the K-3 is going to have more trouble with diffraction? I'm assuming that a 24 MP APS-c camera is going to be more diffraction limited than a 24 MP full frame. How else do you explain the IR results that have the 24 MP D700 200 lw/ph sharper than the 24 MP k-3 using the different versions of the same lens? Ian has even posted images where you can clearly see the difference. It's not a big difference, but it is unmistakable.

Last edited by normhead; 03-23-2016 at 07:45 AM.
03-23-2016, 08:18 AM   #63
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Confusion?

The idea that 8x10 has less depth of field than 35mm etc exhibits a complete mis-understanding of the subject. Depth of field at any particular focal length/f-stop combination is constant regardless of the format. For example: a 150mm lens set at f/16 and focused at 30 ft on an 8x10 camera will have identical DOP as a 150mm lens on a 35mm camera focused at 30 ft. The real difference is the angle of view: 14 degrees on the 35mm and 81 degrees on 8x10 which produces completely different effects of perspective. Crop a 35mm piece out of 8x10 image and it will look identical to the 35mm image, all other conditions being identical (focal length, aperture, distance from camera (film plane) to subject). Compare an ASP-C camera with a FF digital and you conclude that a FF camera has less DOF than an ASP-C using identical focal length lenses. The practical effect is that you should compare angle of view, not focal length. So, a 24mm lens on an ASP-C will be more or less equivalent to a 35mm lens on a FF. To get the same perspective of the 24mm on FF you would need a 16mm lens on the ASP-C. Of course, if you frame your subject identically with the ASP-C and the FF, you will get different perspectives...more image compression with the FF.
You have to be very careful when comparing dof, focal length, angle of view, perspective, f/stop, format, size of final image. Confusion can reign. Every format has its strengths and its weaknesses. What you have to do is choose your framing, camera to subject distance, and choose a lens appropriate to the format you are using.

Last edited by jeverettfine; 03-23-2016 at 08:34 AM.
03-23-2016, 08:27 AM   #64
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QuoteQuote:
The practical effect is that you should compare angle of view, not focal length. So, a 24mm lens on an ASP-C will be more or less equivalent to a 35mm lens on a FF. To get the same perspective of the 24mm on FF you would need a 16mm lens on the ASP-C.
I took that as a given.

When I did my test, I shot 50mm FF and 35mm APS-c. That's why I got more DOF. You're shooting with a different lens for the field of view. A wider lens on APS_c and the wider the lens, the more DOF.

So yes, given that you have to shoot with different lenses to get the same FoV, you get a lot more DoF with the same f-stop on APS-c.

Why are you trying to complicate this?

03-23-2016, 09:44 AM   #65
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QuoteOriginally posted by normhead Quote
The difference between APS-c and FF is a little over 1 stop or 2.25 times if you want to get all dramatic. Hence my opinion that there isn't much difference between them.
Agreed, and I suspect everybody still sticking with Pentax agrees as well, since otherwise they'd be long gone. That said, all my lenses except the Sigma 10-20, the 10-17 Fish, the 18-55 and the 55-300 are FF lenses designed for an FF mount, so there is no way my next body will be an APS-C. When I'm ready for that, the 55-300 will be 'glued' to the K-3 and, for that awesome combo alone, I'm going to keep it.

Last edited by Ikarus; 03-23-2016 at 02:07 PM.
03-23-2016, 10:17 AM   #66
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QuoteOriginally posted by Pl Jensen Quote
Diffraction is a non-issue except for pixelpeeping. There are tons of fine art prints on peoples walls shot well into diffraction. Many of my 645 images are shot at F:22 or 32, and although this can be seen under a high magnification loupe (this is film), in the final print no one can tell. Just apply a tad more sharpening.
you can't see diffraction with film because film resolution is extremely low, you'd be lucky to be recording the equivalent of 12mp with mf film.

see below for the math for when diffraction limits resolution on high resolution cameras.

QuoteOriginally posted by Pl Jensen Quote
I have much more control over DOF with my K3 than my 645NII. This is based on real life experience. In fact, there are images and cant get with the 645 which are easy to achieve with the K3.
we are talking about digital, not film, and crop vs. ff, in this thread, it's comparable because both have good lens availability, while mf is severely limited in that regard.

you aren't providing any kind of specifics there, so it's impossible to determine what you have done.
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03-23-2016, 10:17 AM   #67
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QuoteOriginally posted by normhead Quote
OK someone help me here.... does diffraction become less noticeable of larger formats?

I was under the impressions that diffraction became less noticeable in larger formats, and that diffraction would have more effect on a smaller sensor. Was that incorrect?

I know Ansel Adams and others shot landscapes at 64 and that that would be unthinkable on a K-3, I know my full frame 8 inch by 10 inch cameras achieved narrow DoF wide open at 5.6. I Just assumed there was a sliding scale there.
The scale slides with the crop factor. The calculator here says it all. At the equivalent focal length and f/stop, the diffraction is the same across formats.
03-23-2016, 01:01 PM   #68
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Boy! Digital is a new world when diffraction is such a significant issue. It was never the case with the practical use of film, at least until very large mural prints were being made (perhaps one reason Ansel Adams used an 8x10 for his federal mural project). I suppose that only lens designers and scientists working with extreme resolution technologies were the exception. For practical, general imaging purposes, there is little difference between FF and ASP-C until you reach high ISO settings with large apertures and perhaps long exposures in low light and multi-layer imaging. The whole discussion of technical differences in DoF and f stops between these two formats are unnecessary complications for most photographers. It is kind of like 8x10 used to be, only a small percentage of advanced photographers need be concerned. Am I wrong?

03-23-2016, 01:57 PM   #69
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QuoteOriginally posted by jeverettfine Quote
The whole discussion of technical differences in DoF and f stops between these two formats are unnecessary complications for most photographers. It is kind of like 8x10 used to be, only a small percentage of advanced photographers need be concerned. Am I wrong?
Not wrong, but when you sign up for a forum such as this, you should anticipate encountering a disproportionately large sample of that small percentage of people. When people are passionate about a craft, they tend to be nitpicky about their tools. That's true not just in photography.
03-23-2016, 05:27 PM   #70
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QuoteOriginally posted by Kerrowdown Quote
Some of us... are looking forward to that challenge.
I'll stick the Pentax-K 50/1.2 on the Rayqual adapter and then unto the A7r this weekend and give it a try for laugh. The A7r is an utter dog of a camera mind and one of those few times a workman can reasonably blame the tools.
03-24-2016, 01:17 AM - 1 Like   #71
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One can also use the DXO ”print” vs ”screen” method, so while the diffraction sets in at the same f-stop if one look at the pixel level (if we compare the K-5 with K-1) it will not be as noticeable in a print. If the pictures from both cameras are printed at the same size, that is.

Cramp in 36Mp on an A3 size paper and each pixel will be smaller than if you print 16Mp on the same A3 size paper, and thus less noticeable. So if you look at it that way, you can stop down a FF more before you see the problem in a print.
03-24-2016, 07:21 AM   #72
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QuoteOriginally posted by Gimbal Quote
One can also use the DXO ”print” vs ”screen” method, so while the diffraction sets in at the same f-stop if one look at the pixel level (if we compare the K-5 with K-1) it will not be as noticeable in a print. If the pictures from both cameras are printed at the same size, that is.

Cramp in 36Mp on an A3 size paper and each pixel will be smaller than if you print 16Mp on the same A3 size paper, and thus less noticeable. So if you look at it that way, you can stop down a FF more before you see the problem in a print.
Your comment is completely theoretical with no empiracle evidence to back it up. You have to show that the diffraction is noticeable in a print, before you can show one is less noticeable than the other. First demonstrate that diffraction is noticeable, on a print, not on you screen.

This is one of those issues where those who have actually done prints say the difference isn't noticeable, and the one who have done prints say it is. I'm assuming you fall into the later camp.
03-24-2016, 07:59 AM - 4 Likes   #73
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QuoteOriginally posted by bertwert Quote
I think there are multiple threads discussing this already...

:facepaw:
Indeed! But are the threads equivalent?


Steve
03-24-2016, 08:04 AM   #74
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QuoteOriginally posted by stevebrot Quote
Indeed! But are the threads equivalent?


Steve
Yes, buy only if you print them at the same size!
03-24-2016, 08:35 AM   #75
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And give 1.5x more weight to the threads with APS_c in the title as opposed to those with FF in the title.
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