Canon's early FD rectilinear ultra-wide — the 17mm f/4 from the first FD generation.
The Canon FD 17mm f/4 was one of the first-generation FD lenses launched in 1971 when the FD mount debuted, providing a rectilinear ultra-wide-angle option for Canon's manual-focus system. It sat at the extreme wide end of the early FD range and predates the later Super Spectra Coated S.S.C. revision of the same optic.
This is a manual-focus Canon FD lens with a fixed 17mm focal length and a maximum aperture of f/4. Unlike a fisheye it is corrected to keep straight lines straight, giving a very broad rectilinear field of view. Focus and aperture are set manually on the chrome-nosed early FD barrel.
A rectilinear 17mm delivers an expansive angle of view with controlled distortion, so architecture and interiors keep their straight lines while landscapes gain a sweeping sense of space. The wide field and short focal length provide deep depth of field, making it well suited to environmental and documentary work where getting close and wide is the goal.
On the used market this early FD ultra-wide is less common than mid-range primes. Check for haze, fungus and separation in the complex wide-angle optical group, test the aperture blades for oil and confirm the aperture ring clicks cleanly. Inspect the front element for cleaning marks, and note it adapts to mirrorless via an optics-free FD adapter.