Diffraction Limit

Started Aug 28, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Yep.

Great Bustard wrote:

Anders W wrote:

LTZ470 wrote:

From a very credible source:

"Diffraction thus sets a fundamental resolution limit that is independent of the number of megapixels, or the size of the film format. It depends only on the f-number of your lens, and on the wavelength of light being imaged. "

You think this is a very credible source?


Have a look here:


Bob's post (the second link) is really quite outstanding and to the point. Let's see if I can't sum diffraction softening up more neatly, if not as completely as Bob did:

  • There is no such thing as a "diffraction limit" except when the resolution falls to zero.
  • There is a point where diffraction softening becomes the dominant source of blur, and this point will vary from lens to lens, as well as where in the frame we are looking (the corners typically, but not always, lag about a stop behind the center for DSLR lenses).
  • All systems suffer the same diffraction softening at the same DOF.
  • More pixels, all else equal, will *always* resolve more detail.
  • All systems do not necessarily resolve equally at the same DOF, as diffraction is one of many sources of blur. However, as the DOF deepens, the resolution decreases, and the resolution differences between systems narrows, typically becoming trivial by f/16 on mFT (f/32 on FF and f/5.6 on an FZ200), regardless of how sharp the lens is or how many pixels the sensor has.

Another very good summary. Thanks for taking the time to put this so concisely.

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