mint
Introduction

The Canon 100mm f/2 USM is a fantastic lens.

Not only is it fantastic optically, it has a metal filter thread and forebarrel, and focuses and handles great.

This small and light Canon 100mm f/2 is sharper than the sharpest zoom I've ever used: my Canon 70-200mm f/4 L IS, and it's four times as sensitive to light, letting me shoot with one-quarter the ISO or with four-times the shutter speed in the same situation.

The 100mm f/2 is also inexpensive, less than half the cost of an L zoom, and per my direct comparison, this 100mm f/2 is optically superior to the L zooms.

The 100mm f/2 is an ideal lens for traveling light; a far better idea than any zoom.

The Canon 100/2 is also an ideal lens for when you demand the highest optical performance for high-resolution cameras like the 5D Mark II and 1Ds Mark III.

It handles great: nothing moves externally because focus is internal. For manual focus, simply grab the ring. Handling couldn't be better. This Canon lens from 1991 still out-handles Nikon's current 85mm f/1.8 AF-D.

This is one of the lenses responsible for Canon winning the pro market away from Nikon in the 1990s. Nikon's excellent 85mm f/1.8 AF-D, also still sold today, is a mechanical kludge by comparison. Nikon's lens' focus ring spins around on its own as the Nikon lens autofocuses, so you need to keep your hands off it most of the time, and if you do need manual focus, you have to stop what you are doing and move a switch. If Nikon ever introduces this lens in an AF-S version, Nikon will finally have caught up to where Canon has been since 1991.

The Canon 85mm f/1.8 USM is almost identical in almost every way, except that the 85mm has only a plastic filter thread instead of metal, and a slight difference in focal length and speed. Canon's specifications are out-of-date; when I measured brand-new samples of each lens in 2010, this 100mm weighed only 17 grams (0.6 oz.) more than the 85mm. Get whichever you prefer or flip a coin. My mind was made up by the metal front threads of this 100mm f/2, while others prefer to save the $55 and get the 85mm. Either is spectacular.