The Canon EF 100-300mm f/4.5-5.6 USM is a consumer-grade telephoto zoom for Canon's EF autofocus mount, designed for full-frame and APS-C SLRs. Featuring an Ultrasonic Motor (USM) for quieter, faster autofocus, it was aimed at general telephoto use such as sports, wildlife and outdoor photography.

In the UK auction market today, hammer prices for this lens have ranged from £30 to £75, giving a midpoint of around £52 based on the limited sales recorded. These figures are saleroom hammer results and reflect wholesale rather than retail levels, so clean copies offered through dealers can be priced higher. As a budget EF zoom, it sells for relatively modest sums and its value tracks closely with cosmetic and optical condition.