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DPChallenge Forums >> Tips, Tricks, and Q&A >> Diffraction loss: full frame or only on the edges?
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Showing posts 1 - 7 of 7, (reverse)
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 08/24/2008 12:26:35 PM · #1
I rarely go below F/11 because I've heard you start losing sharpness because of diffraction. It hasn't mattered much because DOF is usually plentiful for most of my shooting.

However, I'm now looking at my first real macro lens, and DOF of course gets tiny, so I want to shoot at smaller apertures.

Hence my question: do you lose sharpness across the whole image, or does it start and the edges and get to the middle only at the smallest apertures? Because I could definitely imagine a tradeoff where getting more in focus near the middle would be worth a little more blurriness outside.

Thanks!
 08/24/2008 04:59:55 PM · #2
Wow. No one?
 08/24/2008 05:10:34 PM · #3
I'm not absolutely positive but believe it's across the whole image and not just the edges. Here is a link to Luminous Landscapes that shows pictures taken with a lens that is supposed to be diffraction limited. The further it was stopped down the worse the image quality of the whole image was. There are some links on that page as well that explain diffraction in more scientific terms.
 08/24/2008 05:27:47 PM · #4
I believe it depends on the lens but is pretty even across the frame. Just remember to get as close to the subject as possible and your image here in DPC size will never show it. I've seen challenge winners that were shot at F22.

Diffraction will become apparent sometimes even below F8 if you are a 200 percent pixel peeper. So it only really matters if you're trying to print or display HUGE.
 08/24/2008 06:37:26 PM · #5
Whole frame
 08/24/2008 09:02:55 PM · #6
Whole frame.

The diffraction limit changes with sensor size and pixel density.

There's a good article explaining at cambridgeincolour site.

ie. A 12mp APS-C sensor will become difration limited at a larger aperture than a 10mp APS-C sensor.

bazz.
 08/24/2008 09:47:53 PM · #7
Cool. Thanks, all, for the info!
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