Quote Originally Posted by Dave Throgmartin View Post
Do you gain that much by having a 36 MP sensor versus a 18 MP sensor?
It depends. If someone never crops, never does any post processing, and never prints larger than 8x10, then they wont benefit from the difference. But the more of those things they do, the larger the difference will be.

Quote Originally Posted by Dave Throgmartin View Post
At what quantity of pixels do even good lenses begin to get max'd out as far as resolving power is concerned?
Most of the cheap ones (e.g. $100 50mm primes and $400 macro lenses) max out at only 500 MP or so, but the more expensive f/2 lenses can hit 1500. Of course, the aberrations and contrast will not be as good as lower spatial frequencies, but some of them can be corrected to some degree in post (e.g. C.A. correction and sharpening). Many lenses have a "long tail" MTF curve, so that although contrast goes down faster than diffraction at first, it flattens out at the highest spatial frequencies.