From DXOMark: More pixels offsets noise3

Started May 30, 2009 | Discussions thread
Kuivaamo Senior Member • Posts: 2,248
Re: Bob..

bobn2 wrote:

Kuivaamo wrote:

bobn2 wrote:

In practice, the 'limit' would be set at a higher
contrast than zero, and we might exclude some esoteric and excellent
lenses, but when the sampling frequency is above the maximum
physically possible resolution of any lens, there is no point having
an AA filter.

If this approach is eventually taken, let's hope Canon won't release
a diffraction-limited 50/1.2; by my quick and dirty estimate we'd
need a 950 megapixel APS-C sensor to avoid aliasing without an AA

True. Thats why I excluded esoteric and excellent lenses. Generally
lenses are aberration limited at wide apertures, and so far as I
know, none even approaches the theoretical diffraction limit at f/4
or so. At that point, aberrations are your friend. I would have
thought 500 pixels/mm (216MP on FF) would be enough to see pretty
much every lens below 10% contrast over its whole aperture range, and
that's within the range of current P&S pixels. Could be wrong, though.

You're probably correct, or close to it anyway. Most DSLR lenses, even very good ones, seem to be mostly aberration-limited even at f8. A truly diffraction-limited lens at f8 should comfortably "outresolve" the 50D sensor, but I haven't seen any tests where this is the case.

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