The EOS-RETRO is a unique adapter for macro photography which allows a Canon EOS mount lens to be reversed on a Canon EOS body, and still retain full lens functions including AF and TTL metering. Reversing a lens on a camera body creates a high quality and high magnification macro lens. For example, a 28-105mm lens reversed will give a range of magnifications from 1:7 at the 105mm end to 2.8:1 at the 28mm end, which is much more flexible than a typical macro lens. And, because a lens is computed to work best at infinity, reversing it means that it gives superb quality at high magnifications.