8 out of 10 points and recommendedSturdy internal focus design, sharp over a wide range of aperturesSome chromatic aberation when wide open
An excellent portrait lens on a full frame body. Quite sharp all the way from f/2.8 to f/16. The ultrasonic ring motor is both fast and quiet, and since focusing is entirely internal, the lens is inherently sturdier than lenses with extending front elements. This is one of my favorite prime lenses for full-frame Canon bodies. It is compact and light enough to be very comfortable to use.reviewed June 25th, 2008
I don't have the 100mm f/2.0, but apparently it's similar both mechanically and optically, so I'd consider that lens as a good alternative, if you prefer a slightly longer focal length. Another option to consider is the 100mm f/2.8 macro. While the macro has better sharpness, I find the wider apertures of the 85mm to be useful in some situations.
3 out of 10 points and not recommendedSmall and lightNot sharp, chromatic aberration
Tested on a full frame body, my copy of this lens seems even worse than average, as it is sharpest at f/16 to f/22, where diffraction normally makes sharpness decrease from its peak. Chromatic aberration and blurry corners make me wonder when I'd ever choose to use the lens. I'd love to have something small and light for hiking photography, but this lens isn't good enough. The noisy auto-focus is annoying, but I'd gladly put up with it if image quality was better.reviewed June 25th, 2008
5 out of 10 points and not recommendedGood focal length, quite fast focusNot durable
Tested on a full frame body, the focus mechanism has become so sloppy that image quality is no longer good until well stopped down. Other reviewers say their copies are sharp from f/2, but my well worn copy is only sharp from f/8 to f/16.reviewed June 25th, 2008
For the price, I think Canon should include a real ring-type ultrasonic motor, as the tiny gears are part of the reason this lens hasn't lasted through the years.
4 out of 10 points and not recommendedSmall and lightPoor corner performance, especially on full frame
On full frame 5D, this lens is fairly sharp at the center from f/2.8, improving a bit as you continue to stop it down, but corners are soft and exhibit CA at all apertures.reviewed July 22nd, 2008
On 1.6 crop 350D, this lens is once again fairly sharp at the center from f/2.8, improving a bit as you continue to stop it down. Corner softness is a problem, but at least it improves substantially as you stop it down.
I used this lens with the 350D for a recent backpacking trip, and found most images required a significant contrast boost in post-processing. The best results came from f/8 to f/16. I suspect a lens hood would help. I'm sure the 17-40 would have produced better images, but the 35 is much smaller and lighter.
I don't recommend this lens for full frame due to the poor corner performance, but for cropped sensors, this lens might be appropriate if you need something compact and light, and are willing to give up some flexibility.