Pixel pitch vs. diffraction limits

Started Sep 4, 2003 | Discussions thread
brian Senior Member • Posts: 1,211
Diffraction effects minimal

8 micron pixel pitch is only 63 cycles/mm. At this frequency a diffraction-limited f/8 lens will give a contrast greater than 60%, which is quite high. You can easily drop down to a 4 micron pixel pitch before diffraction effects start to get really noticeable. On a DX-sized sensor this means you can increase the resolution to at least 24 megapixels and still get meaningful information with good lenses stopped down to f/8 or even f/11.

Brian

michaeladawson wrote:

There was a message posted somewhere... maybe in the Canon forum,
that talked about pixel pitch and its relationship to diffraction
artifacts.

The basic assertion was that a pixel pitch of 8 microns was around
the limit for tolerable images. At this pitch diffraction effects
began to appear at apertures smaller than f/8. If you decreased
the pixel pitch diffraction effects would start to appear at
apertures larger than f/8.

If you believe this assertion and you do the math the conclusion
was that APS sized sensors couldn't really go past 8MP without
introducing serious diffraction effects at larger apertures.

Would anyone care to comment on this? The fact that I have never
heard this before leads me to believe that it is a bunch of bull.
On the other hand, if true, Nikon's APS sized sensors may have a
serious limitation.

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