The used Canon 300mm f/4L IS is a sharp, comparatively small telephoto lens that’s great for travel photography. Key features include:

Five-Foot Minimum Focus. The Canon 300mm f/4L IS boasts an image stabilization system and is easily handheld in decent light. It can focus on subjects as close as five feet away—much closer than most telephoto lenses—allowing it to be used almost as a macro lens.

Teleconverter Compatible. With a 1.4x teleconverter, it becomes a very nice 420mm f/5.6 lens with image stabilization, making it a very nice alternative to the Canon 400mm f/5.6.