SLRGear has a review of the Canon EF 400mm f/5.6L USM telephoto lens, with a verdict that says "The lens performs well, perhaps not up to the level that more recent Canon lenses have, but considering the age of its design it still works extremely well."

The Canon EF 400mm ƒ/5.6L USM was released in 1993, alongside other telephoto primes popular with wildlife and sports photographers. The 400mm ƒ/5.6 is often compared to the more recent 100-400mm ƒ/4.5-5.6L USM IS, the suggestion being that if you are always shooting at the 400mm range, it's better to go with the prime. Our review may help to shed some light on this decision.

The EF lens is compatible with both full-frame and cropped-frame Canon SLR cameras, though on the latter the lens will have an effective field of view of approximately 640mm. The lens features a built-in lens hood, and ships with a well-padded soft case. The lens retails for approximately $1,200.

Read the full review here.