That is the silliest thing I have read in a long time. Like Wayne, I have shoot MFD at f/22 and that claim is so wrong on so many levels. So you are saying we are seeing great images, but actually they are really not good, we are just not seeing it? So if you cannot see the loss of quality, then why the stress on quality that cannot be observed?
I have a feeling the folks stressing absolute technical perfection really do not shoot and print their work. Only the working photographers seem not to be bothered by small working apertures. And if resolving power is really that important to people, I would like to note that my backgrounds and foreground have more resolution at small apertures than large ones--that is what DoF does...
This is one of the funniest conversation I have seen on LL in a while.
It may appear funny to you, but it is based on the laws of physics. Nathan Myhrvold
is no crank, but a genius with a PhD in physics form Princeton University. He is not only an accomplished scientist but an accomplished photographer and gourmet cook--a true renaissance man. That is why I chose to quote him. Of course, one can stop down further with a MFDB than a full frame dSLR, but a few calculations are instructive.
The pixel pitch of the IQ-180 is 5.17 μ, the resolution is 7816 x 10380 pixels, and the sensor dimension is 40.4 x 53.7 mm. The Airy disc diameter for light at 530 nm is 28.5 μ. The sensor becomes diffraction limited when the Airy disc diameter is 1.4 to 2 times the pixel pitch. Diffraction limited resolution of a lens at f/22 is 70 lp/mm at the Rayleigh limit (about 9% MTF) and 33 lp/mm at 50% MTF (figures from Roger Clark). Rayleigh resolution in an astronomical telescope can separate binary stars in this high contrast setting, but is not very useful for terrestrial photography, where an MTF of 50% is more reasonable.
One can use these figures to calculate the resolution of the IQ-180. The Rayleigh resolution at f/22 is 2840 x 3375 lp; since it takes 2 pixels to resolve 1 lp, that corresponds to 2702 x 3592 pixels or 43 MP. For a MTF of 50% the figures are 2702 x 3592 pixels or 9.7 MP.. For the Canon 1DsMIII that Dr. Myhrvold quoted in his post, the Rayleigh resolution at f/22 is 1687 x 2351 lp 17 MP. The MTF 50 resolution is 803 x 1204 lp or 3.9 MP, somewhat better than his prediction of 2MP.
One needs to correlate these figures to the perception of sharpness. According to David Pogue's
tests, megapixels are not as important as often believed, so it is reasonable to get good results at the 9.7 MP you would get with the IQ-180 at f/22.