Re: Spot size in relation to pixel size

On May 30, 4:21 pm, jfl...@xxxxxxxxx wrote:
I've often read that it is wise to check a lens design's spot size,
particularly when designing a digital camera system. Can anyone tell
me if the spot should be smaller than the sensor's pixel, or what a
reasonable criteria would be? Perhaps its related to the Rayleigh
criterion?

Thanks.

Making the spot diagram fit within a pixel boundary is overkill. Not
that it doesn't happen from time to time, but you should not hold
yourself to this standard. In the worst case (defocus) a lens meeting
this requirement would have almost 70% contrast at the Nyquist
frequency.

In general I dislike the use of spot diagrams, and usually like to
keep MTF at Nyquist about 40-50% or more, but if you want really good
results you should try for 80%+ contrast at half-Nyquist and just
ignore what happens at higher frequencies.

.

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