This macro bellow is compatible with Canon EOS traditional film and digital SLR cameras.The macro bellow is inserted between the lens and the camera body.Bellows are best used with a tripod for stability and ease of use -allowing you to smoothly and constantly adjust the distance between your camera and the object you want to photograph. There is a UNC 1/4screw at the bottom allowing the bellow to be mounted on top of a tripod. This product is a step up from the macro extension ring and is invaluable for anyone wishing to take extremely close-up pictures,particularly those of plants and flowers. The rail can be extended up to 150mm. Magnify ratio is 0.74-2.86:1 while using an f50 lens, and is1.32-5.1:1 that of f28 lens. Specifications Flex (mm): 37-144 Photography zoom (change to standard lens to f50): 1/1.3x-2.86x Focus mode: knob, gear, rack drive, lock button Focus value: a staff guage with slier Other frame: jack, 1/4"tripod screw Size(mm): 100(W)*106(H)*160(L) Compatible with: Canon EOS 35mm film or Digital SLR cameras Canon 5D/ 30D/ 20D/ 10D/ 350D/ 300D/ 400D/Rebel XT/ Rebel XTi/ D60/ D30/ 1V/ 3/ 5/ 33/ etc.