Review by Klaus Schroiff, published March 2010

Special thanks to Johannes Matzke for providing this lens!

Introduction

Compared to its predecessor the lens has been redesigned into a true IF (internal focus) construction - the physical length of the lens remains constant regardless of the focus setting. It may not have the tank like construction of its L grade cousin but the build quality is very decent based on a metal mount and an outer barrel made of good quality plastics. The front element does not rotate so using a polarizer is not problem. The broad, rubberized focus ring and has smooth, pleasant operation although manual focusing is a little tricky due to the short focus path.

It is possible to attach an optional tripod mount to the rear of the lens. While not really required the tripod mount provides a better balance - otherwise the camera- lens combination tends to be somewhat front-loaded specifically when used on light-weight DSLRs.

Typical for ring-type USM lenses full-time manual override is always possible in one-shot AF mode. The AF speed is blazingly fast but Canon still provided a focus limiter in order to avoid any AF hunting into the extreme macro range when operating the lens at normal focus distances.

Here's a spec comparison between this 100mm lens and its "L" grade cousin: