Canon FD 35mm f/2 S.S.C. (convex)

There are two versions of the Canon FD 35mm f/2, and one of them is mildly radioactive. This is the other one. The early lens is identified by a dished, concave front element, and it uses thoriated glass elsewhere in the formula, the kind that browns to amber over the decades and ticks on a Geiger counter. The redesign swapped that front element for a convex curve, and that single change is the whole reason people hunt down this exact version. Same fast 35mm, none of the yellowing.

A 35mm lens on a film SLR has to clear the swinging mirror, so this is a retrofocus design, and like most fast retrofocus wides of its era it gives up a little wide-open bite to buy that extra speed. Expect it to be soft and glowy at f/2, with the center usable rather than crisp and the corners loose, then to firm up as you stop down, sharpest somewhere in the f/5.6 to f/8 range the way these old wides usually are. I would not promise you lab numbers for this specific variant, because nobody really tests them that way, but that is how it behaves in hand. The Super Spectra Coating earns its keep here, holding contrast better than you expect from a Seventies wide and keeping flare manageable when a streetlight parks itself in the corner.

What keeps it on the camera is the way it draws. Color comes back neutral with a faint warm cast, contrast sits moderate instead of clinical, and the backgrounds fall apart gently instead of breaking into busy edges, which matters more on a wide than people admit. This is a reportage focal length and it acts like one: environmental portraits, street, the kind of frame where you want context around the subject and a fast stop held back for dim rooms.

The f/2 is the practical reason to carry it over a slower 35. Shoot a bar or a dusk street and you can open all the way and still hand-hold. Meter for that moment in Zone Light Meter with the aperture set to f/2 and you see exactly what shutter speed the available light leaves you before it is gone. The 55mm filter thread is shared across much of the FD line, so one set of NDs or a polarizer covers this lens and several of its siblings.

The real weakness is the mount, not the glass. Canon walked away from breech-lock FD in 1987 when it moved to the EF system, so no Canon SLR with a digital sensor ever accepted these, and that orphaning is exactly why they stay cheap. Mirrorless rewrote the ending. The short flange of Sony E or Fuji X lets a plain adapter reach infinity, and FD glass got a second career on those bodies. Cross-shopped against the Olympus OM 35mm f/2 and the Nikkor 35mm f/2, the Canon holds its own, and the orphaned mount keeps it inexpensive on the used market. Just check the front element before you pay. Convex is the one you want.