photoman43

I also agree with the above.

But I always test my specific lens and camera to see what actually happens. The tests are done using a tripod, ball head and remote shutter release. I test each f stop on the lens. Do not assume that if you see diffraction at f 11, all smaller f stop openings( larger f numbers) will have more diffraction. That may not be the case. My tests have been done with various Nikon macro lenses over the years. And now that I have a Z9 I have to do the tests all over again.

Joexx

I disagree. Diffraction is only caused by the size of the aperture (lens opening). Think of it this way. A crop sensor can be thought of as just a portion of a larger sensor (ie Full Frame). if you look at the portion of the FF sensor that is in the area of the FF that is the crop sensor area, the diffraction has to be identical because you are looking at the same exact area. The diffraction is (by definition) caused by the bending of light thru an aperture. At the time of the bending, it has no idea what size sensor it is going to hit.

Yes, on the outer edges of a FF sensor (past where the crop sensor area does not exist), depending upon the lens, you may see different distortions. But this is not an equivalent comparison. check out these links for some of the math, http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/cirapp2.html http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/Raylei.html#c1 No mention of the target area (sensor area) because it does not matter.

MJPerini

Diffraction is real, and a Physical property of optical systems, but it is GENERALLY not something you need to worry about. There are many things that affect image sharpness, and if Maximum Sharpness is your goal then optimizing all shooting parameters including camera stability and optimum aperture is important.
But diffraction should almost never be a 'Primary Concern' like being there for, and framing a good picture.
We all know that all lenses have optimum apertures-- generally a few stops down from wide open, but that doesn't (or shouldn't) stop us from shooting wide open or stopped down when the creative or technical need arises.
It IS a bit more of a problem for smaller formats, and less so for larger formats. View cameras were routinely shot at f/45 & f/64 (they even had a club.......) (The longer the Focal length the larger any given focal ratio will be)
Pinhole Cameras are the extreme, and nothing in them is perfectly sharp, but lots can be acceptably sharp.

In Modern digital cameras & lenses, in most situations, Diffraction is not a problem. Having said that , we also know that our lenses are at their best at moderate apertures. So when possible it makes sense to use them.

jackm1943 Loc: Omaha, Nebraska

Diffraction sets in much earlier with macro. I have a 4X f2.0 macro lens that is great at f2.0 and f2.8, but noticeable diffraction sets in at any larger f stops.

Urnst Loc: Brownsville, Texas

Thanks for the thoughtful and informative responses to my questions.

PierreD

No criticism, just trying to understand the basis for your statement that (everything else being presumably the same), the diffraction effect would necessarily be worse for M4/3 than FF. Thanks.

FZ200 Loc: New York

"Theory and practice are the same in theory, but different in practice." :-) :-)

TriX Loc: Raleigh, NC

What you are missing is that smaller sensors have smaller pixels for the same resolution, and diffraction occurs when the Airy disc diameter exceeds 2-3 pixels. Therefore for a given size or Airy disc, larger pixels (associated with larger sensors, everything else being equal) produce less diffraction for a given aperture and wavelength of light.

Architect1776 Loc: In my mind

So pixel size is the determinant.
So a D850 would be far worse than a D780 and have failure much sooner as the aperture closes down and get quite fuzzy quicker than the D780.
Good to know.

User ID

But diffraction occurs even when using Panatomic X or K25. So, you speak not about when it actually *occurs* but of when it becomes bothersome to digital pixel peepers. Its a practical difference.

burkphoto Loc: High Point, NC

Yeah, there is a theoretical diffraction limiting aperture, then there is what you can tolerate under normal circumstances, then there is what you do if using a small aperture is your only choice...

I carry ND3, ND8, and ND10 neutral density filters for Micro 4/3 work, mostly so I can use 24 fps video in bright sun and not have to stop down if I don't want to.

imagemeister Loc: mid east Florida

Same with me and the RX10m4 ........

imagemeister Loc: mid east Florida

Yes, I AGREE for your case but, The KEY for you to think about is practical in the field use "for equivalent FOV ! ! It MUST be qualified as to what exactly we are talking about - which is what confuses people ! !
That is why I say size of sensor size does NOT directly affect diffraction ! - but it DOES indirectly - for FOV !
.

Joexx

With all due respect,diffraction is not worse for M4/3 than a FF. I think everyone is misunderstanding what diffraction is. Diffraction is caused by light going through an opening. It changes depending upon the wavelength. With diffraction due to passing through a circular aperture, there is more diffraction as the circle gets smaller. Smaller corresponds to a larger F stop. Think about it? if diffraction is ONLY caused by the smaller opening, how can it increase because somehow the light wave "knows" at a later point in time, it will hit a smaller or larger sensor. Answer . . . It Cannot. Therefore, the size of the sensor has NO bearing on the diffraction caused by the aperture opening.... hyperphysics.phy-astr.gsu.edu/hbase/phyopt/cirapp2.html

Joexx

I still disagree. FOV has nothing to do with diffraction due to the lens opening. That is what the discussion is. It is not "apparent" distortion due to all sorts of things or different FOV. And also, the depth of field also has nothing to do with the size of the sensor. So bringing in FOV really is not relevant. Sorry, I am not giving you a hard time, but there is just lots of misunderstanding about the meaning of FOV & depth of field. All of these 'things' have very specific math equations (& not very complicated ones) and NONE of them have anything to do with what happens later when the electromagnetic wave hits a sensor at a later time.