jradose wrote:
I have read numerous articles about diffraction. I have watched numerous videos about diffraction. I still have mixed thoughts about just how much of a problem it really is, and what, if anything, can be done if it is a problem. Some authors of articles and/or videos say diffraction takes a toll on image quality, and they suggest you don't shoot narrower than an F/16 aperture. Others, have a differing view. I will cite Bryan Peterson (I love his "You Keep Shooting" videos) constantly suggests shooting at F/22 (or higher if your camera allows). So, asking fellow Hoggers, what is your take on diffraction.....a problem to be concerned with, or no discernable problem, shoot F/22 for more DOF?
I have read numerous articles about diffraction. I... (
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If you are a landscape photographer, diffraction is more of a problem than if you shoot macros.
Details in rocks and tree leaves and other "stuff" when shot at a distance will get irrevocably lost when there is diffraction. Mild diffraction can be dealt with by manipulating micro or high frequency contrast, but severe stuff will make you think your camera is broken.
On the other hand, when shooting macro or close up, your image will have detail that is unexpected, such as the setae (hairs) on insect legs, barbs and barbules on a bird's feather, etc. Even a fairly small aperture will still capture this with surprising detail. Of course, opening the lens to the optimum aperture will do a better job, especially in a side by side comparison.
Diffraction is a term used to describe the phenomenon of how light spreads after going through a hole. Smaller hole=more spread=more diffraction=less detail captured=softer image. Diffraction is the antithesis of the pursuit of sharpness - particularly those who choose pricey gear, don't use UV or clear filters in the light path, and obsess over precise focus by resorting to the fine focus tuning features in their cameras.
In the simplest of terms diffraction is based on lens aperture and pixel size or Circle of Confusion - these are easily represented as precise measurements Airy Disk diameter for the lens, and Pixel diameter or CoC for the camera's sensor. Smaller apertures will record a larger a Airy Disk size, and vice versa. A camera with a large pixel size - cannot resolve really fine detail anyway, so it can tolerate a larger Airy Disk than a camera that has a smaller pixel. When the Airy Disk exceeds the size of the CoC, there will be diffraction. If the amount the size of the larger Airy Disk is close to the size of the CoC, the loss of sharpness will be modest. The larger the Airy Disk is relative to the CoC, the higher the image degradation. Typically, an expensive lens is equally susceptible to the effects of diffraction as a more modestly priced lens.
Diffraction is constant for subject to camera distance, aperture and pixel size and has nothing to do with lens brand, focal length or camera brand - btw - so F22 on one camera and lens will be EXACTLY the same as F22 on another camera and lens as long as the pixel size is the same. So if one were using a 50mm lens at F22, the same amount of diffraction would be present as if one were using a 200mm lens at the same aperture on the same camera, or camera with the same pixel size.
When you dig deeper into how diffraction works, there are other factors that will contribute to the perception of sharpness - overall sensor size/print size (a smaller sensor will seem less sharp when you try to make a big print), viewing distance of the final image (the greater the distance between the image and the viewer the harder it will be to pick up flaws), image content (images with a lot of texture and detail will look worse than a wide-view sunset), viewer's eyesight, print surface, lighting where prints are viewed, etc.
This is a very thorough treatment of the subject of diffraction, and offers some simulators and calculators to help promote a better understanding, and more importantly, dispel some widely held myths.
https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm