Is Diffraction Really A Concern? Locked

Started 2 months ago | Discussions thread
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Doug Haag Senior Member • Posts: 2,535
Re: Is Diffraction Really A Concern?

alcelc wrote:

Diffraction is very real and can affect IQ.

However, it is sensor size dependent. When APSC or FF would see negative effect from diffraction on f/22, M43 has it started around f/11 having f/8 been the usual edge of performance.

I did a home testing on the M43 system I use, and images (SOOC JPG) were softened noticeably from f/11 onward for normal range of shooting. I had started a thread on M43 forum @ https://www.dpreview.com/forums/post/63900203

TBH an image which has been affected by diffraction could still look reasonably sharp. We can only find a diffraction affected image softer than one without diffraction on nearly pixel peeping level of comparison. Therefore if the DoF will out benefit the softening by diffraction, we can stop down as small as we have to.

If you do sharpening in post (apply by RAW Converter), the softening could be eliminated.

In the mean time, I also found the diffraction limit could be pushed (from f/11 to f/22 in case of M43 system) for close up shooting. My another thread on M43 forum about this @ https://www.dpreview.com/forums/post/65137203

My 2 cents.

Thank you for finally pointing out in this thread that the amount of diffraction blur at a given f/stop varies with the sensor size (FF vs APSC vs 43).

I use a special depth of field calculator program that incorporates a diffraction blur measurement.  It suggests that for my Nikon APSC sensor, an amount of diffraction blur that I would find unacceptable kicks in north of f/11 but prior to f/16.  It would be a little sooner for the slightly smaller Canon-sized APSC sensor.  If I switch the software to reflect a full frame sensor, the same diffraction effect doesn't kick in until just above f/22.

This appears somewhat consistent with your tests.

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Bob
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