Canon's FD budget telephoto — 300mm f/5.6 for basic telephoto reach on film.
The Canon FD 300mm f/5.6 is a budget telephoto prime for Canon's FD-mount film SLR system — providing 300mm reach at the most affordable f/5.6 aperture. The most basic telephoto option for serious reach in the FD system.
Optically adequate for casual telephoto use — the 300mm provides useful reach for nature and sports from a distance. The f/5.6 maximum aperture is very slow — limiting use to bright conditions. Manual focus at 300mm requires careful technique.
Canon FD mount with 55mm filter thread at approximately 580g. Manual focus and aperture. The FD mount adapts to mirrorless cameras via simple adapters but does NOT adapt to Canon EOS without quality-reducing corrective optics.
Available used for almost nothing — budget telephoto for FD film system or adapted mirrorless. The f/5.6 is very limiting in low light. For casual FD telephoto needs or mirrorless adapter enthusiasts wanting cheap manual telephoto reach.