The Canon EF 100-300mm f/4.5-5.6 USM Lens is a mid-grade long telephoto zoom lens.
Introduced in 1990, the 100-300 is built reasonably well. The finish does not appear modern, but the build quality is decent. A metal lens mount shows that the 100-300 is not a bottom-of-the-line lens.
AF is very fast and quiet. The Canon EF 100-300mm f/4.5-5.6 USM Lens utilizes Ring USM (Ultrasonic Motor) focusing, and FTM (Full Time Manual) focusing is an included feature. The MF (Manual Focus) ring is very small and wobbly – It is not as easy to use as it could be.
The zoom ring, on the other hand, is too easy to use. The 100-300 will extend all by itself when hanging downward.
At 1.2 lbs, the 100-300 is a mid-weight lens. It feels substantial in your hand.