bleirer

The confusion arises because it depends on whether you are pixel peeping or not. At 100% viewing diffraction affects the image when the Airy disk covers 2-3 photosites, so smaller photosites means a greater effect sooner, but in viewing normally if the same image area is covered by more photosites because of higher megapixels the pic can still look sharp because it relates to viewing distance, resolution, and the visual acuity of the viewer.

Click advanced on the calculator near the bottom to see the difference https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

bleirer

It's not related in any way to shutter speed but it is related to aperture size, the smaller apertures show diffraction sooner if the photosites/pixels are tiny. But since too slow of a shutter can give subject motion blur or camera shake blur you won't notice softening due to diffraction anyway. When you can't blame the loss of sharpness on shutter speed and the aperture was small, it could be diffraction. It is a gradual softening though, not a bright line at a certain aperture.

cameraf4 Loc: Delaware

Purposely. Yes, I admit that with today's PP software it is certainly possible to "make a silk purse out of a sow's ear." But as a "photographer", I always would rather make the most detailed image I can SOOC. It will be much easier to Tweek later.

anotherview Loc: California

Agree: "It's not related in any way to shutter speed but it is related to aperture size"

anotherview Loc: California

Yes: "I always would rather make the most detailed image I can SOOC. It will be much easier to Tweek later."

BebuLamar

With a high pixel count sensor and you do pixel peeping you can see minor camera shake as well as minor diffraction. However, when display or print an image of the same size as a lower pixel count camera it would look at least the same if not better.

larryepage Loc: North Texas area

This is one of several photographic principles that is difficult to discuss rationally. To fully understand what is happening, it is necessary to understand the source of diffraction. Years ago it was part of the standard physics curriuculum, but it has been a number of years since I have even seen it mentioned. It is a phenomenon which arises because of the interference of light traveling two paths of slightly different length. The most common place it occurs (and the easiest way to create it) is by passing light through a very narrow slit. It is possible to demonstrate this to yourself by passing a fairly bright light (no...not the sun...not ever) through a slit made by holding two of your fingers very close together and looking at it withy your eye very close to the slit. If you are good (and lucky) you will be able to see alternating dark and bright lines rather than a uniform field of light.

Diffraction also occurs at a single edge.The effect is just much less and much harder to detect. Diaphragm blades in a lens present such a single edge, so effects of diffraction are always present in every image of every lens at every f stop.

The question if visible diffraction arises, then, from two different sources. One of them turns out to be pretty much meaningless most of the time, but the other can, on some occasions, be real.

Single edge diffraction can sometimes be real. The defining parameter, since there is diffracted light in every lens all the time, becomes "of all of the light falling on the sensor, how much of it is diffracted light, and how much of it is not?" Since the diffracted light comes only from the tiny slice right next to the diaphragm edge, it should be clear that lots and lots of pure, unadulterated light can pass through a lens with a wide aperture, while much less pure light can pass through a small aperture. (Of course the length of aperture gets shorter at small apertures too, but it varies linearly, while the area of the opening varies as the square of the diameter of the opening.)

Slit diffraction, on the other hand, is much less important in a lens. Diffraction through a slit can be really impressive in a laboratory demonstration. But being able to see it requires three things: a very narrow slit (1 mm or even less), which means a pretty bright light source, and finally, monochromatic light (like a yellow sodium vapor lamp or a visible laser, usually a red one). A 300mm lens set at f32 has an aperture opening of just more than 9mm. That's way too wide to produce any detectable slit diffraction. A 14mm lens set at f22 has a diameter of about 0.7mm. It might create a tiny amount of detectable diffraction in some really high contrast situations.

It is certain that a high resolution sensor is capable of "seeing" things that a lower resolution sensor cannot. Quite frankly, without that distinction, there would be absolutely no reason to pursue or purchase higher resolution cameras. When printed to the same size (and to a size that is achievable by the lower resolution sensor), there should be no significant difference in the appearance of integral flaws. There should also be no important visible differences when viewing a larger high resolution image at the equivalent apparent size. Close inspection of a larger print will always reveal more shortcomings, even when comparing between two prints made from images from the same camera.

Now...considering motion and shutter speed. It is not debatable that higher resolution cameras are capable of "seeing" smaller things...smaller details and smaller movements. Sometimes this is important and sometimes it is not. For me, it can be. I do night sky photography. An important fact to understand about stars is that they are "point sources" of light. They have no width and no height. When properly focused through a good lens, the light of one star will fall on exactly one pixel. This is true regardless of lens focal length or telescope magnification. (It is different from planets, which because they are closer to us do have width and can be magnified into images of finite size.) It is the main reason that stars "twinkle" and planets do not. It has been demonstrated that even with very short focal length lenses, stars quickly move from one sensor to the next if exposure times are too long. The result is that the ability of a high resolution sensor to record individual stars exceeds that of a lower resolution sensor, just as we would expect. But it also means that this ability can be easily lost if the shutter is left open too long, resulting in the same star moving across two or more sensor elements. So the long established "Rule of 500" for exposure times for the night sky has been supplanted by a new "Rule of 300" for cameras with sensor sizes greater than, say 30mp or so. That doesn't mean that a photographer can't use the Rule of 500 any longer, just that more ideal results will be achievable by limiting to the shorter exposures.The same principle which led to this revision would also be applicable to managing other camera or subject movement, which might or might not even be applicable, depending on the subject matter.

Any way...I have found that what has been said about higher resolution sensors is true. But depending on what you are doing, it may or may not matter.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

My grandmother had an expression- translated- Don't mix hominy grits and poppy seeds- it ain't a good tasting recipe. So it is in photographic technique. Sometimes information gets out there where unrelated issues are blamed for poor results or certain bits of information are omitted from the hypothesis or method leading to a false conclusion. Sometimes it is just misinterpreted.

Too slow a shutter speed in certain conditions can lead to blur or image degradation due to camera movement, vibration, or subject movement- this has nothing to do with pixel count, grain, or basic image resolution.

If the photographer is concerned about diffraction, which usually occurs smaller apertures, he or she may increase the shutter speed to attain a wider aperture which may preclude diffraction- this also has nothing to do with sensor type or pixel count. The same applies to increase the shutter speed to enable a wider aperture for reductio of the depth of field or selective focus.

In photography, there are lots of coincidental effects and affects. This requires the astute photographer to isolate the effects of the intrinsic characteristics of the camera/sensor/pixel count, or the films charismatics-such as gran and resolving capabilities and even processing aspects, the specifications of the lens as to aberrations and diffraction thresholds, and the causative reasons of blur and image quality loss due to poor technique and camera handling.

Also- when shooting, there are oftentimes compromises that have to be made- you have to juggle ISO, f/stop, shutter, speed in terms of depth of field, lens performance, noise/grain, subject motion, available camera support and more. Separate the grits from the poppy seeds.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Generally speaking, the less the megapixels, the better the camera in low light situations. My Nikon D3s, a 12 meg camera still blows away it's 24 meg cousins in low light, go figure.

talborough Loc: Bellingham, MA, USA

...So higher MP cameras will likely show the degradation of image sharpness at larger apertures,...

=====

Gene, The excerpt above from your explanation saved my EOS R from a lot of shelf time. Now, I get sharp. Many thanks. Tom

rmalarz Loc: Tempe, Arizona

I think the reason for the higher shutter speed would be to minimize the movement of the camera during exposure. However, if using a tripod, just about any shutter speed would work.

Now, if the Northrups told me what time it was, I'd hope to have an accurate watch to check for myself.
--Bob

larryepage Loc: North Texas area

Ed--

Thanks for your amplification here. I was just trying to express that there is some "room" in what proper exposure looks like. For instance, trying to avoid blowing out specular highlights in reflections from chrome, or from light sources in a night cityscape are not necessary and can make things needlessly difficult just for the sake of a histogram.

Bison Bud

I too have often wondered about the need for the higher and higher MP counts on the new sensors offered and where sensor sizes might actually become a matter of diminishing returns, if not a determent to overall performance. It's long been discussed that larger pixels do a better job in low light conditions and now it appears that these high MP sensors may be more sensitive to diffraction as well. I personally see low light performance as a big issue in making my camera choices and also believe that many of today's lenses aren't really capable of resolving their images to the point needed to really take advantage of many of the new extreme pixel counts, at least not lenses that I can ever hope to afford and own.

At some point, the physics of the whole thing has to come into play and in my opinion we're there now or have already past it to some degree and wonder just where others believe the point of diminishing returns might actually exist. There is also the matter of file sizes need for the higher MP sensors although for me that's more a processing time issue than and overall storage issue, but they do both come into play. In any case, the manufacturers are indeed playing a marketing game with MP's, but I will admit that they seem to do a pretty good job of offering high performance at many levels of sensor sizes. Until and unless the consumers object to pushing the MP limits higher and higher, it's going to be one of the primary tools in their marketing arsenal. Good luck and good shooting to all.

george19

[quote=bleirer]The confusion arises because it depends on whether you are pixel peeping or not. At 100% viewing diffraction affects the image when the Airy disk covers 2-3 photosites, so smaller photosites means a greater effect sooner, but in viewing normally if the same image area is covered by more...(snipped)

Something missing from all these inputs: usually, the higher pixel count the higher the density to fit them all on a sensor.

When the aperture size gets closer to the pixel SIZE, diffraction will creep in, because any edge will induce diffraction. When all you have is diffraction, the image has no choice but to be blurred.

At a large aperture, most of the light passing through is away from the edge...no diffraction.

I don’t understand the point about shutter speed however...makes no sense.