This is an original Canon FD mount 50mm f/1.8 prime lens. It was primarily sold with the Canon AE-1 single-lens reflex (SLR) 35 mm film camera, but fits any vintage FD mount camera. It was sold as the "New FD" lens (FDn) because it introduced the new square mount locking button, making it easier to mount and dismount the lens from the camera. It was made with a lightweight plastic body, and its size and weight was reduced, making it among the smallest vintage 50mm SLR lenses (mounted, it extends 40 mm and weighs 160 g without caps). It was a popular lens and had a long run from 1979 to 1991, well into the EOS mount era. It has a minimum aperture of f/22 using a 5-blade iris, and the glass has Canon's Spectra Coating (SC), which like many vintage lenses, is prone to flaring when shooting in the direction of the sun without a hood. It takes 52mm filters. It is a popular lens to adapt to modern mirrorless digital camera, and is a favorite among videographers because of its lightness, 180 degree focus throw, and good image quality. Because of its short flange distance, it requires corrective lens adapter for EOS to achieve focus at infinity; with a dumb adapter, it becomes a macro lens with dumb adapters.
This example was tested and is in great condition with only light wear to the body, and no scratches, fungus, or haze on the lens. There are a few specs of dust inside, but this does not affect image quality. There is no oil on the iris blades, and everything works well and smoothly. The image with the aperture wide open was achieved with a FD to NEX adapter attached. It comes with an original Canon rear cap and a generic 52mm front cap.
Fast vintage prime lenses are a great value, offering good image quality and a vintage look, at a reduced cost compared to modern lenses. The sample images here were taken with a Sony NEX-5 with the lens wide open at f 1.8. Outside this required shooting in partial shade at 1/3200 sec; the inside photograph of the shells was taken with dim ambient light, handheld, at 1/50th second. At f/5.6 image sharpness improves appreciably.