Macro Extension Tube set for Sony Alpha / Minolta film & digital SLR is composed of 3 extension tubes - 9mm, 16mm, and 30mm with male and female Sony / Minolta bayonet adapters. Mount the tubes between lens and camera body to get your choice of macro ranges - 8 combinations in total. Mounting Extension Tube in between the camera body and lens will create more distance between the lens and film plane. By moving the lens further away from the film or digital camera sensor, the lens is forced to focus much closer than normal. The greater the length of the extension tube, the closer the lens can focus. Use this set with your normal lens and you will get the quality, which is as good as the original lens and the size, sharpness and versatility is perfect for the macro and close-up pictures. This Macro Extension Tube set does not have electrical contacts and does not preserve the automatic diaphragm. You need to use manual focus and manual exposure while shooting. The newer cameras and digital SLR"s will automatically go to the manual metering mode once you have the tube set on.