Canon EF 75-300mm f/4-5.6 III USM Autofocus Telephoto Zoom Lens - USA

Rating:
Summary: most affordable 300mm
Review: This is definitely the best buy for that kind of range (75-300mm), although it doens't have IS (Image Stabiliser), which means that you must use a tripod when using your lens at full zooming capacity (300mm) or have a left arm made of plastic and hold your breath!

All in all, it's quite bright (f5.6 at 300mm) which means you get decent amount of light at full zoom, allowing you to get clear shots of a hare in a pretty dark wood, to set an example. But don't try to shoot indoors with it, it wasn't built to nor meant to (unless you have a studio and like shooting portraits from afar).