Why do my photos look softer at f/22 than at f/14 on a tripod?

Asked 1/9/2013

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I’m shooting evening scenes on a tripod with a Nikon D3000 and comparing the same composition at different apertures. I expected the tripod to keep everything sharp, but I’m noticing that smaller apertures like f/14–f/22 look softer than wider settings. For example, at 62mm, an image at f/14 looks sharper than one at f/22. Is this because I’m stopping down too far and not letting in enough light, or is something else causing the blur?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

13y ago

2 Answers

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You've hit the diffraction limit. That link has some amazing answers with a lot of detail, so I won't be redundant, but in short, once the aperture gets to be below certain physical size, diffraction causes inevitable blur. For your camera (and any other camera with an APS-C-sized sensor), the limit is a little beyond f/11.

The amount of light let in doesn't really matter. If that's the case, your image will be underexposed, but this effect will happen in either case.

The bad news is: you can't really do anything about this. But, you might still get an overall benefit in across-the-frame sharpness — the overall sharpness may be a bit lower, but near and far details may be closer in sharpness giving a more unified appearance. See Do smaller apertures provide more depth of field past the diffraction limit, even if peak sharpness suffers? for more.

The good news is: you now know your equipment better, and can decide if sharpness of the point of focus is more or less important than depth of field for a given scene.

Also, if your goal in stopping down is actually to take a longer exposure in bright light, take a look at What are neutral density filters and how do I use them to create long exposures in daylight?

Originally by user1943. Source · Licensed CC BY-SA 4.0

user1943

13y ago

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AI Answer

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What you’re seeing is most likely diffraction, not camera shake or simply “not enough light.” As the aperture gets very small (high f-number), light bends more at the aperture blades, which reduces fine detail and makes the image look softer.

On an APS-C camera like the Nikon D3000, diffraction can start to become noticeable around f/11 and gets more obvious by f/16–f/22. So it’s normal for f/22 to look less sharp than f/14, even on a tripod.

A smaller aperture still increases depth of field, so sometimes the image may look more evenly sharp front-to-back, but overall crispness can drop.

How to avoid it:

  • Don’t stop down more than necessary.
  • Try using apertures around f/8 to f/11 for best overall sharpness.
  • If you need less light but not more depth of field, use an ND filter.
  • If you truly need much more depth of field, you may have to accept some diffraction, or use specialized options like a tilt-shift lens.

UniqueBot

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13y ago

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