Canon FD 50mm f/1.8

Canon's FD lens mount arrived in 1971, and a 50mm f/1.8 was part of it from the start. The Canon Camera Museum lists the first version as marketed in March 1971. It had a chrome front ring, six aperture blades and a weight of 305 g. Eight months later a second version added an aperture lock lever on the back. The optical recipe never changed. Every version uses six elements in four groups, a double-Gauss layout according to Flynn Graphics' comparison of the four early versions. What changed was the barrel. In March 1973 the S.C. version dropped the chrome nose and came in at 255 g. In March 1976 the S.C. (II) went further. It used more plastic, lost the lock lever, weighed 200 g and cut the aperture to five blades. In June 1979 Canon replaced it with the New FD 50mm f/1.8. The museum record gives 170 g, a 52 mm filter thread instead of 55 mm, and a smallest aperture of f/22 instead of f/16. The mount changed too. Older FD lenses lock with a rotating chrome breech ring. On the New FD lens the whole lens turns until a release button clicks out, as Canon's own lens instructions describe. The surprising part is how little the pictures changed across all of this. A lens that lost almost half its weight between 1971 and 1979 kept the same six pieces of glass.

A first lens for any FD body. It is light, simple and focuses down to 0.6 m (about 2 ft), according to Canon's records for every version. Stopped down, it is a sharp lens. Flynn Graphics tested an S.C. (II) against a modern EF 50mm f/1.8 and called the FD lens outstanding at f/8. Adapting to mirrorless cameras. Phillip Reeve used the New FD version on a Sony E-mount body through a plain adapter and reports that it focuses to infinity without issues. Carrying. The New FD version weighs 170 g and is 35 mm long, per the Canon Camera Museum. Where it falls short Wide open it is soft and low in contrast. Phillip Reeve's review of the New FD version describes glow at f/1.8 and a busy, outlined background at longer distances. Flare. The same review found large ghosts with the sun in the frame, which it puts down to the simpler S.C. coating. Coma in night scenes. Reeve recommends stopping down to f/5.6 to clear most of it. The five-bladed aperture on the S.C. (II) and New FD versions gives pentagon-shaped highlights. The 1971 to 1973 versions have six blades. The last versions use more plastic. Reeve describes the New FD barrel as feeling cheap next to the earlier ones.

Set the aperture ring to f/16 or f/22 and look into the front while you work the aperture lever on the back. The blades should snap shut and spring back open at once. A pause, or blades that hang at a middle setting, usually means oil on the blades. Phillip Reeve's guide to manual lens defects warns that slow blades are a real problem on a film SLR. The shutter can fire before the blades reach the set aperture.

This is often normal. An FD lens holds its aperture wide open until the camera, or an adapter, moves the lever on the back. On breech-lock versions the aperture can also stay inactive while the mount ring sits in its unmounted position, as one repairer documents. Test the lens on a body or a good adapter before judging it.

Owners report this on New FD versions when the rear section has been turned while the lens was off the camera. Press the release button on the side of the mount, turn the rear section until the red dots line up, then mount it. Canon's instructions for New FD lenses describe the same red-dot alignment.

Shine a flashlight through the lens from behind and look at an angle. Fungus shows as thin branching threads. Haze shows as an even milky veil. A few specks of dust do not affect pictures.

Turn the focus ring through its whole range. It should feel even from 0.6 m to infinity. Stiffness usually means the helicoid grease has dried. Play or grinding points to wear or damage.

The A setting has a lock button, and Canon's instructions say to press it while turning to A. On New FD lenses, keep the ring off A when the lens is used on an adapter or with older accessories.

Cause: oil on the blades slows them down. One repairer documents an S.C. version whose blades paused at about f/5.6 before opening fully. Fix: the blades are cleaned with isopropyl alcohol, which Phillip Reeve's defects guide calls one of the simpler repairs. A proper job takes the aperture unit out. Workshop job for most owners; a confident hobbyist can do it.

Cause: usually not a fault. The adapter's locking ring has not been turned, or a New FD lens is set to A. Owners on the MFlenses forum report that the aperture cannot change until the adapter ring is turned firmly. Fix: turn the adapter ring to its locked position and set the aperture ring off A, as Canon advises for use with accessories. No repair needed.

Cause: storage in damp conditions. Reeve notes fungus grows when humidity stays above about 70 percent. Canon's own instructions say to store the lens in a cool, dry, dust-free place. Fix: the lens is opened and the affected elements cleaned. Hydrogen peroxide and alcohol remove most growths, but some fungus etches the coating for good. Workshop job.

Cause: the cement between two bonded elements breaks down. A repairer who overhauled several S.C. versions describes lenses hazed in the cemented part as beyond saving. Fix: re-cementing is specialist work and rarely worth it on this lens. Surface haze on separate elements, by contrast, often cleans off. Check before buying.

Cause: dried grease in the helicoid. Fix: the helicoid is taken apart, cleaned and regreased. Mark the starting position of each thread first, because the same repairer warns that reassembly otherwise becomes trial and error. Workshop job or careful DIY.

Cause: a DIY repair gone wrong. The aperture ring clicks on tiny ball bearings with springs behind them. The same repair notes warn they fly out easily and can only be replaced from a donor lens. Fix: a donor lens. This is the main reason to leave the rear of the lens to a technician.

Cause: decentering, an element out of line. Phillip Reeve's review copy of the New FD version was decentered. Fix: realignment is difficult and few technicians offer it. Test by photographing a flat, detailed subject and comparing the corners.