This is a telephoto macro lens developed as part of the FD replacement lens series. With full-aperture metering and automatic diaphragm coupled, the lens can be used for shooting from infinity to 1/2x (0.45m) without accessories and from 1/2x to life-size (0.40m) when used with the FD50 Extension Tube.
As telephoto macro lenses have a long focal length, close-ups can be made without actually approaching the photographed object, increasing the range of applications from those of a standard macro lens to include photographs of ecology of insects and animals and plants in addition to macro photographs requiring lighting.
A modified Tessar lens is adopted in the optical system, and appropriate power distribution of the lens is used for compensation of spherical aberration, field curvature, chromatic aberration and distortion, which is particularly important for close-up lenses. Because of this, there is little variation in aberration depending on shooting distance and the lens offers excellent image-forming performance from infinity to life-size. Although macro lenses normally tend to have a large amount of extension, this lens features light and smooth focusing together with a compact lens barrel achieved by incorporating new mechanisms into the helicoid and diaphragm unit.