The Canon FD lens mount is a physical standard for connecting a photographic lens to a 35mm single-lens reflex camera body. The standard was developed by Canon of Japan and was introduced in March 1971 with the Canon F-1 camera. It served as the Canon SLR interchangeable lens mounting system until the 1987 introduction of the Canon EOS series cameras, which use the newer EF lens mount.
This is a lens that has aberrations specially corrected for extreme close-up work. The lens focuses all the way from infinity to as close as 23.2cm (9.1 in.) without additional attachments providing 0.5X (1:2 reproduction ratio). It will fill the 35mm frame with a subject only 48mm x 72mm (1.92 x 2.88 in.). By adding extension tubes or a bellows you can even focus close enough to shoot at 1:1 magnification or as high as 3:1. At 1:1 the image is life-size, that is, the size of the object on film is equal to the object's actual size. Entering the world of photo-macrography at 1X, this range extends up to 20X. Beyond that is photomicrography which is accomplished using a microscope and an adapter.
This is a USED lens. There are signs of age on the barrel, but the glass is free of any visible marks. Overall great condition. Manual Focus lens.