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10-14-2010, 10:36 AM   #1
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K-5 possible diffraction limitations

Hi,

I was reading the following (to me very interesting) thread on dp: nikon D3x :" is this what it's all about?" [Page 1]: Nikon D3 - D1 / D700 Forum: Digital Photography Review
It is an interesting story about a D3 user who bought a D3x, expecting to buy the best available camera in the market.
He is a jewellery photographer, who needs lots of DOF, so he uses f40.
The D3xs results were so much worse than the D3 results, that he returned the D3x to the shop (with a loss).

The rest of the thread is about the fact that this photographer ran into the diffraction limits of the D3x higher sensor pixel count (smaller pixels actually).
A D3x just cannot handle f40, due to the diffraction because of the high pixel count!

There are several references to other Internet sources on the subject of diffraction.
One being: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks
It has a diffraction limitation calculator...

I filled in the diffraction calculator for my planned K-5 purchase. Assuming:

Maximum print size: 30 cm (appr. A4 paper size / my PC screen size)
Viewing distance: 25 cm
Resolution: 16 Mega pixels
Camera type: DSLR 1.5X

After trying several apertures, the calculator shows that the images will be diffraction limited starting from F16!!

If you want to see the impact of diffraction, there is a link to: Understanding Lens Diffraction in the thread as well.

Would a K-5 with only 10Mpixels not have been better??
Or should we all have to move to FF for 16 Mpixels in order to be able to use F22??

- Bert

10-14-2010, 10:49 AM   #2
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Interesting but besides jewelery photographers who uses f16 or above?
10-14-2010, 10:52 AM   #3
raz
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bymy141 if you are worried about diffraction, just shot at 10Mpixels then or shoot normal size and resize your images to 10 megapixels after you shot.

It will be the same as shooting with a camera with a sensor of 10Mpixels.
10-14-2010, 11:30 AM   #4
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QuoteOriginally posted by WerTicus Quote
Interesting but besides jewelery photographers who uses f16 or above?
Many other macro photographers, I presume

That being said, unless viewing images at 100%, I don't think the effects of diffraction are really all that noticeable in actual use.

PS.: switching to a larger sensor does not really change things if you keep the same resolution. The diffraction limit may be farther in theory, but in practice you'll have to stop the lens down further to get the same DOF as you had with the smaller sensor, and the end result will be the same.

10-14-2010, 11:33 AM   #5
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higher resolution sensors will always capture greater or equal detail, all else equal

Diffraction is an optical phenomenon that is linked to the lens and not the sensor. The diffraction limit is something used to decide what aperture to use on the same sensor, not to be compared against other sensors. I made a crappy graph here: http://imgur.com/9xtyR.png

The physical size of the airy disk that causes the softening is independent of the medium that it is being projected on to. A higher resolution sensor will capture more softening on a per pixel basis, but the overall image will not be softer, as the absolute physical size of the airy disk being captured will be the same on both sensors.

For more information, see the discussion here:
How do you find out the "sweet spot" of a lens - Photography - Stack Exchange

Last edited by Eruditass; 10-14-2010 at 11:48 AM.
10-14-2010, 11:51 AM   #6
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QuoteOriginally posted by WerTicus Quote
Interesting but besides jewelery photographers who uses f16 or above?
Aside from bad jewelery photographers, no one. Except maybe macro photographers that are unable to focus stack due to the situation.

Last edited by Eruditass; 10-14-2010 at 11:56 AM.
10-14-2010, 11:59 AM   #7
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He owns a D3 and is stupid enough to shoot at F/40? I guess this world is filled with people who have money to buy the equipment but never properly learn how to use it.

If I was a jewelry photographer, photo stacking would be a no brainer. Highest possible IQ, and its pretty dang easy to do with inanimate objects.
10-14-2010, 12:03 PM   #8
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Or T/S lens instead of f40

10-14-2010, 12:11 PM   #9
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confused

I will be the first to admit, I am confused by this whole post.

I understand difraction, and note that it is not a magical thing that happens at F16 and smaller, but that it is always present, it is just that the ratio of the area impacted by difraction is a much larger percentage of the image at small apertures that it begins to dominate.

Additionally since this is a lens problem, pixel count, or specifically pixel density should not be an issue, AND, considering the pixel densityu of a P&S camera and the very very small apertures if it is killing the D3x than no point and shoot should work at all, yet they do. This is especially true considering how small the aperture is physically on a P&S.

As for having print size in the equation, to me, it seems that we are discussing similar issues to depth of field, with respect to when a sharp detail begins to degrade and look fuzzy with magnification.

Could it be that the whole issue here is that increased pixel resolution is causing things to appear less sharp, only because there are more pixels now in the detail, what once looked sharp because the detail was only 2-3 pixels wide could look blury when there are 10.

I think someone is spending way too much time in front of the computer as opposed to behind the camera

just my $0.02
10-14-2010, 12:51 PM   #10
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Hi bert,

Life is full of compromises. I have very few lenses that go beyond f22, and none that go past f32. I've never, in 6 years of shooting DSLRs, used f32. I'll use f22 or more shooting macros and sacrifice a little resolution to diffraction for additional DOF if needed.

A better solution has been to add a TC and shoot at greater subject distance with the same magnification. IMO, this is not a practical limitation to the camera, and like most "limitations", can be worked around with a little creative thinking and photographic knowledge.

I think a lot of people get bogged down with technical intricacies that have little to do with practical photography -- like how the image looks at 300% on screen as opposed to how it looks in their actual target medium -- like an 8x10 print. Digital photography has encouraged this, and it's a good thing as this has forced incredible improvements in potential IQ in just 10 years. It's also raised a generation of photographers who obsess about trivial technical details. . .

I recently went to see an Henri Cartier Bresson exhibit at the Art Institute of Chicago. Not my style of shooting, but what a head slapper when it came to comparing his perception to my by-the-book "standards" of IQ and composition. . .This really opened my eyes. . . very few prints larger than 8x10, compositions that would make most trained artists cringe, motion blur and grain, lots of shots of backs of people's heads. . . and an attention to detail and in many cases a sense of humor/irony that's just astounding. . .What great learning experience to discover just how much there is yet to learn. . .

Scott
10-14-2010, 01:17 PM   #11
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QuoteOriginally posted by bymy141 Quote
Hi,

I was reading the following (to me very interesting) thread on dp: nikon D3x :" is this what it's all about?" [Page 1]: Nikon D3 - D1 / D700 Forum: Digital Photography Review
It is an interesting story about a D3 user who bought a D3x, expecting to buy the best available camera in the market.
He is a jewellery photographer, who needs lots of DOF, so he uses f40.
The D3xs results were so much worse than the D3 results, that he returned the D3x to the shop (with a loss).

The rest of the thread is about the fact that this photographer ran into the diffraction limits of the D3x higher sensor pixel count (smaller pixels actually).
A D3x just cannot handle f40, due to the diffraction because of the high pixel count!

There are several references to other Internet sources on the subject of diffraction.
One being: Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks
It has a diffraction limitation calculator...

I filled in the diffraction calculator for my planned K-5 purchase. Assuming:

Maximum print size: 30 cm (appr. A4 paper size / my PC screen size)
Viewing distance: 25 cm
Resolution: 16 Mega pixels
Camera type: DSLR 1.5X

After trying several apertures, the calculator shows that the images will be diffraction limited starting from F16!!

If you want to see the impact of diffraction, there is a link to: Understanding Lens Diffraction in the thread as well.

Would a K-5 with only 10Mpixels not have been better??
Or should we all have to move to FF for 16 Mpixels in order to be able to use F22??

- Bert
Am I the only one that reacted that the viewing distance of 25 cm? Who inspects a print that close. Its closer to the print than the print is wide. Most people feel uncomfortable focusing there eyes that close
10-14-2010, 02:03 PM   #12
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I don't want to do the mods job, but why is this in this area of the forum? It isn't anything unique to the K-5, but a general photographic issue to do with diffraction, lenses, optics etc. The thread title suggests there is some unique problem with the K-5 in relation to diffraction being discussed, which isn't the case
10-14-2010, 02:16 PM   #13
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Original Poster
QuoteOriginally posted by raz Quote
bymy141 if you are worried about diffraction, just shot at 10Mpixels then or shoot normal size and resize your images to 10 megapixels after you shot.

It will be the same as shooting with a camera with a sensor of 10Mpixels.
Changing the image output to 10Mp will not change the sensor pixel size.
So I do not see how that will change the physics here, or do I miss something?

- Bert
10-14-2010, 02:17 PM   #14
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Original Poster
QuoteOriginally posted by WerTicus Quote
Interesting but besides jewelery photographers who uses f16 or above?
I do shoot macro f16 - f22 *a lot*.

- Bert
10-14-2010, 02:22 PM   #15
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Small pixels doesn't "create" diffraction, they can only pick up finer detail such as diffraction. Downsize the picture and the finer detail is gone again.
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