05-15-2011, 12:41 PM
No direct experience, but you can test the approximate background blur degree of the 100/2.8 by stopping down and cropping from the 85/1.8. This only applies to the big picture level of course, and not at pixel level. Note using f/2.5 instead of f/2.8 is probably needed to compensate for the effectively smaller sensor from the cropping action during this simulation. Unfortunately this same trick can't easily be done for the 135/2 as I'd estimate you'd need to crop from an 85/1.3 for indication.
<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.