Diffraction Limit

Started Aug 28, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 42,079
Re: Diffraction Limit

Anders W wrote:

Steen Bay 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:


It's correct so far though that it's the f-stop that determines the size of the 'blur circle' and therefore the theoretical max resolution measured in lp/mm on the sensor with a perfect lens on a sensor with an unlimited MP count. In that sense the diffraction is independent of the sensor size, but it also follows naturally that a larger sensor will have a higher potential resolution at e.g. f/4 than a smaller sensor, simply because it's larger (lp/mm x sensor height in mm = lp/ph).

Yes, but the qualification you made (which can also be expressed as a matter of magnification, the image from the smaller sensor has to be magnified more for the same final display size) is pretty important, wouldn't you say?

In fact, it is critical.

And as you can see from the second of the two links I provided (if you hadn't seen it already), that's hardly the only problem with McHugh's presentation.

Too many relate the effects of diffraction to the size of the pixel as opposed to the proportion of the photo the Airy Disk spans.

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