Originally posted by Digitalis you are basing your argument on the resolution of the camera sensor - not the lens.
No, I'm basing it on knowledge of optics. All else the same, the FF lenses will have ~50% better resolution. It's tough to measure that across different cameras because the megapixels are not the same between cameras, in general.
Originally posted by Digitalis The canon 85mm f/1.2L is hardly the best example of optical excellence, I always compare 50mm f/1.4 lenses - because every manufacturer makes one, and they typically perform quite well from f/2.8 to f/11
The 50mm f/1.4 performs 1-2% better than the 85mm f/1.2 on the 50D, and about 1-2% worse on the 350D, so I think it's within testing error. The 50mm is also much simpler to make, of course, so I'll stand by my no-slouch-of-a-lens comment.
Center Resolution, Canon 50mm f/1.4 USM on 350D: 2064 (Peak Performance for the lens)
Center Resolution, Canon 50mm f/1.4 USM on 50D at f/4: 2598 (Peak Performance for the lens)
Center Resolution, Canon 24-105 f/4 on 5DII at 70mm, f/5.6: 3359 (wide open is slightly better, other mm's are slightly better, but this is the number closest to comparable number given)
Center Resolution, Canon 24-105 f/4 on 5D
III at 70mm, f/5.6: 3800? Higher? If the lens was perfect (obviously it isn't) we'd expect quite a bit more, of course.
I don't expect the higher megapixels to improve the 24-105 as much as the 50mm did, because of course the base lens is slightly inferior, but the change in format size swamps that out when comparing FF to APS-C.
Last edited by ElJamoquio; 10-17-2012 at 07:17 PM.