Diffraction: A Concept Every Photographer Should Understand

Diffraction is something that can rob your images of sharpness, and as such, it is important to have a functional understanding of what it is and how to avoid it. This excellent video explains what diffraction is and how it varies based on different parameters.

Coming to you from ProAV TV, this helpful video will explain the concept of diffraction. You have probably noticed that very few photographs get taken past an aperture of about f/11 or so, even if the photographer needed more depth of field. This is almost always due to diffraction, which will cause a softening of the image as your aperture gets narrower and which is why you should try to avoid ever stopping down your lenses to very small apertures like f/22 or f/32.

Diffraction is a physical phenomenon, and as such, there is no way to engineer our way around it. And while you do not need to understand the complex physics behind it, it is important to have a practical knowledge of when you can expect it to appear and what you can do to work around it. Check out the video above for the full rundown. 

If you want to calculate the diffraction limited aperture for your specific camera, check out this helpful calculator from Photo Pills. 

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11 Comments

Leon Kolenda's picture

What about the Diffraction settings on some camera models, Nikon Z's and some Panasonic cameras?How does that work?

Leon Kolenda's picture

So when would you use the diffraction feature in-camera, f11 and above?

Stuart Carver's picture

Cant wait for all the APS-C vs FF arguments on this one... its always a joy reading that utter bullshit.

I shoot at f/32 all the time on my D810 and I like to ask photographers to look for any diffraction effects. Still looking. To illustrate diffraction effects Ansel Adams used an aperture that's about 250 microns. At 400 microns the image is still sharp. Of course that was film. But try it you may like it. The issue is not the amount of light that gets through the aperture it's the size of the aperture relative to the wavelength of light. It's true that with small apertures the Airy disk will cover more pixels. So if you really care about individual pixels maybe there is a point. I

Jason Flynn's picture

That’s interesting because I can see my images start to soften around f/11 when shooting high detail scenes like cityscapes. Got any examples or better yet comparison shots at f32 and f8?

At f/11 with, say, a 110mm lens your aperture is roughly 20000 times the wavelength of light. So sin(theta) approx 1/20000 for the Airy disk. Pretty much all of the landscapes on my Instagram page were shot at the minimum aperture of the lens. f/22 or f/32. At f/32 I can focus on infinity and have the near field in focus too. I'll do an f8 vs f32 image subtraction some time. Of course YMMV. Cheers.

Steve Gunn's picture

I thought ansel adams always shot at f16 and made the sharpest photos ever created.

No, look up Group f-64 on Wikipedia.

Steve Gunn's picture

he still shot most everything at f16 & f22..point was --the contrast to what this worthless article is about..

Steve, his medium format cameras like the Hasselblad typically only go to f/22. Large format cameras (8x10 for example) typically go to f/64. This is because the Airy disk spreads geometrically and the distance from aperture to film is greater. To get the same size Airy disk at the focal plane you need smaller apertures. See volume one of his book. When he was shooting large format landscape he used very small apertures. E.g.book 1 figure 9-6 f/45. Even in close-ups like figure 9-9 he used f/32. Do you have a reference to what he shot "most" of the time? I just have his books. And landscapes. Portraits are a different issue.