The Canon FD 100mm f/4 Macro is a fixed focal length lens designed for close-up photography, compatible with the Canon FD SLR system. This lens allows for a native magnification ratio of 1:2, which can be extended to 1:1 through the use of dedicated extension tubes. The optical configuration is optimized to correct common aberrations at short focusing distances, ensuring uniform sharpness from the center to the edges of the frame. The maximum aperture of f/4 is constant and the diaphragm consists of blades that ensure smooth bokeh. The all-metal construction reflects the professional standards of the time, with a focus ring featuring a generous throw that allows for critical precision, essential in macro applications. The lens maintains high performance even in general use as a moderate telephoto lens, thanks to the anti-reflective coating that reduces ghosting and flare in incident light conditions.