Canonflex and FD lenses

I've fitted FD lenses to a Canonflex and noted no ill effects but hesitate to recommend such use. On the other hand, the Canon R system was less than two years out of production when Canon began designing the FD system. I think the Canon designers probably considered such mixed usage and designed accordingly. At least I hope they did...

'A' series and later cameras-- including the F-1N-- are incompatible with certain earlier lenses.

For some lenses, the mount is incompatible. (In some cases the lens would damage the mirror.) With other lenses, the camera's meter won't work. Canon provided a list of incompatible lenses in each camera manual, and I've tabulated it for three representative cameras below. Note this list is almost certainly incomplete, so use caution with old lenses, even when no incompatibility is noted.

I don't know if there are incompatibilities the other way around-- i.e. if there are FD lenses which are incompatible with Canonflex R or Canon FL cameras.

It's been my experience that all FD lenses, breech ring and breech-bayonet mount, are backward compatible with any FL mount camera. On an FL body, the automatic diaphragm and stop-down metering functions are identical whether you're using an FL or FD mount lens.

While I have Canonflex bodies and lenses, I've never gotten around to testing the compatibility between the first generation R mount with the FL and FD generations. One major complication is that the breech-bayonet mount FD lenses do not have the built-in manual aperture feature that the breech ring lenses have. If you use a New FD lens on a Canonflex, you'll need to lock the diaphragm lever in some manner. Otherwise, you'll only be able to use the lens wide open. I'm not sure if Canon's Manual Diaphragm Adapter interferes with the Canonflex aperture mechanisms.

My curiosity was piqued, so I tested a New FD 35-70mm f/3.5-4.5 lens on a Canonflex. There was no interference between the camera and the lens. The body's aperture mechanisms and the lens' levers and pins have sufficient clearance during shutter winding and shutter tripping. However, the lens cannot be mounted when the Manual Diaphragm Adapter is attached to the lens, which means that New FD lenses can only be used wide open on a Canonflex body unless you rig your own adapter.

Thank you for the responses. After reading them I had the confidence to mount my FD Pre-S.S.C Chrome nosed 35mm f/2 and it mounted and fired with no problem. The aperture stopped fine manually (I didn't really think I could get open aperture/auto stop down functions anyway). So Yes! it works in stopped down mode. Yahoo!
Now I have the Super-Canomatic R 50mm f/1.8 and I can use my old FD breech lock 35mm f/2 and 135mm f/2.5, in stopped down mode, until I find some of the original Canomatic lenses. It's just a viewing issue since the on-board Selenium meter is uncoupled and, in fact, there is nothing in the viewfinder but the picture. What a beautiful classic Canon camera this is, and in near mint condition to boot. Thank you for all for your help.

No question, the RM's a rakish devil...Canon stylists did a great job with it.
Alas, finding really clean R-Series lenses with working apertures is no small feat so I just use FLs instead- they maintain some semblance of period-correctness which complements these Canonflexes while bettering their original optical performance.

It's not uncommon to find Canomatic lenses, as well as older FL lenses, with mechanical problems. If the lens has not been physically damaged or infested with fungus, the culprit is usually a simple lubrication problem. Fortunately, R and FL lenses are much easier to disassemble for cleaning than FD lenses. All of the R and FL lenses with bad diaphragms that I've repaired had oily, gummed up blades. None had bad springs or broken parts, not surprising once you open up one of these lenses and see the quality of the finish and materials used for these parts.

Of the Canonflex family of cameras, my favorite is the RP, a straightforward and honest camera. The removable prism on the original Canonflex and the R2000 is of rather limited utility though its black finish does lend these models a distinctive appearance. The RM has its own unique characteristics, but I like the funkiness of the base plate winders.