04-24-2011, 08:33 AM
Just quickly skimming various reviews here for Canon APS-C, fast primes seem to peak around f/4. The 85/1.2 is the only one I've found so far that has a relatively good performance at f/2.8, but even then it is only comparable to f/4 not better. It is curious that full frame centre results also peak around f/4, but border performance seems to lag a stop or two behind.
<a class="bbc_url" href="http://snowporing.deviantart.com/">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.