Canon EF 100mm f/2 USM

Everyone knows the EF 85mm f/1.8 USM. Far fewer people clock its quieter sibling, the 100mm f/2, which Canon shipped in 1991, three years into the EF mount. The two look like they came off the same line: black polycarbonate barrel, ring-type ultrasonic motor, 58mm filter thread, eight rounded blades. The family resemblance stops at the glass. The 85 is a nine-element, seven-group design; the 100 runs its own eight elements in six groups. Canon built this one to give the EF system an affordable short telephoto that focused fast and stayed light, and that brief never really changed across thirty-plus years of production.

The rendering is why it stuck around. It is sharp wide open at f/2, genuinely so, not the apologetic kind where you stop down to f/4 before the lens wakes up. Centers are crisp from the first click and corners catch up by f/8. Those eight rounded blades keep the diaphragm close to circular as you stop down, so out-of-focus highlights stay round instead of going pentagonal, and the background falloff is smooth without the nervous edges some cheaper teles produce. Color is neutral, distortion is close to nonexistent. Chromatic aberration is well controlled too: shoot wide open against a bright rim and you can coax out a little fringing on the highest-contrast edges, but it stays slight and edge-confined rather than the kind that wrecks a frame. Stop to f/2.8 and even that mostly disappears. The more practical limits are the ones the spec sheet hints at, not the optics.

It has always lived in the cheap-but-genuinely-good tier. People cross-shop it against the 85mm f/1.8 and against the much pricier 135mm f/2L, and the 100 splits the difference: a little more working distance than the 85 for head-and-shoulders, a lot more portability and a lot less money than the 135. Headshot and event shooters reach for it because the ring USM snaps to focus and the longer focal length flattens features in a flattering way. The extra reach also buys you distance, enough that your subject relaxes and forgets you are there. For candid portraits that matters more than the spec sheet suggests.

The catches are real. No image stabilization, no L-series weather seal, and the barrel feels exactly as plasticky as the price implies; it also flares more than you would like into a strong light source without the hood. One thing it does get right: focusing is internal, so the front element does not rotate, and polarizers behave. None of the omissions hurt the pictures. They dent the resale story a little, which is part of why the lens stays a bargain on the used market.

At f/2 on film you are often shooting dim rooms where reflective meters get fooled by a bright window or a dark suit. Meter the skin tone you actually care about and place it deliberately rather than trusting an average. Zone Light Meter's spot reading lets you put a face on Zone VI and let the background fall where it lands. Wide open on a fast short tele, that single placement decision tends to carry the whole frame.