Rab-Eye wrote:
I'm revisiting Bryan Peterson's classic Understanding Exposure, and it reminded me how often he shoots at f/11-22. I obviously can't ask him why diffraction does not seem to be a problem for him, so I am asking here. Is diffraction at small apertures overblown as an issue? Is it more of a problem under certain conditions and less so under other conditions? A confused mind wants clarification.
Thanks,
Ben
It depends on the context... my favorite answer for all of photography and life.
The smaller the sensor, the worse the diffraction at wider apertures.
If you are looking for it and comparing images of the same subject taken at the same time at different apertures:
Based on 20 to 25 MP sensors, diffraction annoyance starts:
> Around f/8 on Micro 4/3.
> Around f/11 on APS-C.
> Around f/16 on full frame.
> Around f/22 on medium format digital.
Higher megapixel count sensors may show diffraction at wider apertures.
Degree of enlargement matters.
Whether you're a pixel peeper, or not, matters.
Lens cleanliness matters.
Lens coatings matter.
Subject contrast and brilliance matter.
Lens corrections and sharpness matter.
Your experience may vary from mine, so it is recommended that each of us make our own tests to determine a "diffraction limiting aperture." I avoid using smaller apertures than those listed above, when I can.
I'll add that MEASURABLE diffraction occurs at wider apertures than those I listed, as evidenced by Tri-X' graphs, below. That's one reason I say, make your own tests to determine what you'll accept in your circumstances. I came up with my "rule of thumb" answer by doing that over the years.