Conclusion: This lens is very well built, it may not be fully sealed but in my opinion that's the only thing stopping this having a red ring. The lens does not move either the front or rear element for focussing which means it is naturally reluctant to attract moisture or dust internally. The proper ring-USM focuses nearly immediately, it's frighteningly sharp even wide open, the Boke and low light ability is lovely thanks to its wide aperture. What would I change?
Pros: Fast auto-focus, Superior build quality, Super-sharp images, wide aperture
Summary: I shoot portrait and weddings so this lens is right in my wheelhouse. I owned one of these for a couple years and it always served me well. It's an excellent lens for headshots as well as that super shallow DOF full body portrait. It compares well with the 135/2.0 in that department. Focus is quick, color and contrast are great.
Love it: Canon EF 100mm f/2 USM Telephoto Lens for Canon SLR Cameras
4 December 2013
Summary: The 85mm f/1.8 and the 100 f/2.8 are highly rated, but hands down, the 100mm f/2 lens is the most underrated Canon lens there is. Mine is sharp, fast, and has wonderful bokeh! It is as good as the 85mm f/1.8 and has more reach for sports. I have had mine for several years and continue to be impressed with the images that this lens produces.
Summary: LOVE, LOVE, LOVE. This is my new BFF and I can't imagine life without her. Sharp images. Picture perfect and all at F/2. I was surprised given the price and wondered if I would have buyer's remorse, but this lens quickly became my favorite and I am thrilled. Perfect for shooting landscapes or portrait subjects from a further distance. I find this lens very beneficial when photographing children so you aren't in their space and you can still capture beautiful moments.
Summary: I like to occasionally shoot pics of people and did have the 135 f2 L lens. Very heavy when mounted on my 5DM2. I wanted something lighter in weight. This lens, while light weight, is surprisingly sharp and well made. Wide open (which is how I like to shoot) this lens has very nice blur (bokeh) yet your subject will be sharply in focus. This lens does not come with a lens hood/shade.
Summary: Very sharp, focusing speed is very fast. Chromatic aberration is not good when outside, but can be corrected with software. Same with vignetting. No noticeable distortion. Bokeh quality is okay. Overall excellent value.
Summary: This is a great lens for the price. You get near L series lens picture for less than 1/2 the price. I have shot high school sports, both indoor and outdoor. I also shot portraits. Just a great overall lens.