Cameralabs.com skriver bl.a.:
Canon’s EF 500mm f4L IS USM is a super-telephoto lens adored by wildlife and sports photographers alike. The 500mm focal length, equivalent to 800mm when mounted on a cropped-frame body, delivers decent-sized images of distant subjects, while the f4 maximum aperture allows you to isolate them with a very shallow depth-of-field. As one of Canon’s top-end professional lenses, the build and optical quality are excellent: the lens can handle tough conditions, while delivering well-corrected images even with the aperture wide-open on full-frame bodies.
The EF 500mm f4L IS USM is understandably large and heavy compared to mainstream lenses, but in super-telephoto terms is actually considered to be comparatively light and compact. Indeed it’s comfortably smaller and lighter than the next model up in the range, the EF 600mm f4L IS USM, and selected in preference by those who may need to hike with it for any distance or attempt an occasional handheld shot. Don’t get us wrong, you wouldn’t want to handhold or hike with a 3.87Kg lens for long, but it’s a world-apart from the 5.36Kg heft of the 600mm f4L in portability, not to mention being 69mm shorter and around 20% cheaper too.