Ilya Zakharevich wrote:
With proliferation of half-frame 10MP cameras, a natural question is:
what is the MP count starting from which the higher resolution of the
sensor does not help to *significantly* improve the total lens+sensor
resolution. Of course, this depends on the lens, so it makes sense to
discuss the diffraction-bounded region of f-stops.




resolution [#] similar (?) to about 1.6x increase of MP count.

So with such a sensor, one gets (for SLR fixed-focus lenses):

f/22: 10 MPixel sensor;
f/16: 20 Mpixel sensor;
f/11: less than 40 Mpixel sensor;
f/8: about 40 Mpixel sensor (assuming lens resolution
saturates near f/8).

Makes sense. Most camera lenses are not that great when it comes to
their optical quality. Otherwise, they would maximize their resolution
at their widest opening, there would be no overbearing aberrations to
require the lens be stopped down to f8.


Similarly, with rangefinder-type lenses, the beginning-of-leveling-out
point would be about 80MP (needed at f/8 and f/5.6 shots).

[#] (Actually, removing AAF would also *significantly* increase
sensitivity [measured via the exposition needed to achieve a
certain visible S/N level], but this deserves a separate message...)

You'll find that professional optical sources are more "honest" about
what is needed to support high megapixel count cameras with small
pixels than consumer camera makers. You need a lens capable of at
least 100lp/mm to support a 5um pixel size. I doubt 1/4 of the lenses
offered by most mfgs meet this spec. So, what is someone going to do
with 80 megapixels?