What's the difference between the mounts?

Alright I know there are at least 3 mounts that have the same breech-

lock attachment mechanism, namely the R, the FL, and the FD. What

are the differences between these three in terms of capabilities?

What are the mechanical differences in terms of levers, pins, etc?

Also what are the differences if any with those few AF AC-mount

lenses made for the T-80?

Steven,

 

All share the same breech function and dimensions.

 

The R lenses came first, with the Canonflex. I'm out of my depth here, but I believe I've heard they have an automatic aperture lever that operates in the reverse direction from the later lenses. Someone will need to correct me here!

 

FL lenses came next, in 1964 I believe. They too have only an automatic aperture lever, the one at the bottom of the lens mount, but it operates in the same way as the later lenses. They can be used with FL or FD bodies, but metering must be done with the lens stopped down because the meter has no way to know what the lens' full aperture is.

 

FD came in 1971, was updated in 1981. It has the auto aperture lever at the bottom, an aperture signal lever at the side, a full-aperture signal pin in between, the AE switch pin at about 4:00, and a reserved pin.

 

The camera operates the auto aperture lever to close the diaphragm at exposure. The actual resulting f/stop opening is determined, in automatic mode, by the position of the aperture signal lever, determined in turn by the camera, based upon the meter reading. In manual mode the signal lever just rides along with the aperture ring setting. The signal lever is used a bit differently in the F-1.

 

The full aperture pin depresses a plunger or lever in the body in proportion to lens speed. The faster the lens, the longer the pin. The AE switch pin just operates an on/off switch in the camera, telling it whether the lens is set to "A" or not.

 

As far as I know, the reserved pin was never put to use, though they are not all the same length across a variety of lenses. I've wondered if it might have been eventually intended as a minimum aperture signal, which would have eliminated some of the guesswork when the camera indicates an overexposure problem at, say, f/22, not knowing that the mounted lens has f/32 as an option. Or maybe to indicate a focal length range? Anyone have any ideas here?

 

I'd also be guessing about the AC lenses as far as additional interface.

 

There were some FL lenses that are not usable on FD bodies, namely non-retrofocus wide angles that protrude into the mirror's path. There are some listed as being incompatible with the camera's meter, but I'm not too sure what's going on there.

I don't believe there's much difference between FD lenses and the AC lenses made for the T80, save for the autofocus capabilities of the AC lenses. One thing to note: the AC lenses were in permanent automatic mode (always set to "A," and could not be put into manual mode). I don't know if an AC lens could be used on, say, a T90 or other FD-lens body, but I also don't know of any reason they could not. If the autofocus interface coupling on the lens (a series of contacts) has clearance with the camera's workings (mirror, etc.) there's no reason that an AC lens wouldn't work just like any other manually-focused FD lens in "A" mode.

The problem is with those pins; when going from the R to FL mount; either they get munched up; hung up; or other weird thing. I remember that some combos work fine; others not at all...My friend has a R mount 1959 camera; I will have to inspect and check out the R mount next time I vist. I believe there is no problem with a bellows; or preset lens; or T mount; just the pins can get in the way when using R mount lenses on newer cameras.

The reserved pin, to the best of my memory, is set for the range of available f/stops. So a 50/1.4 that stopped to F/16 would have the same reserved pin as a 135/2.8 that stopped to F/32. In both cases the pin would reflect a 7 f/stop range.

With a few exceptions the R & FL lenses should fit and operate on later bodies in fully manual mode. R lenses had a dual iris control lever arrangement that was different from the FL & FD lenses. From the limited number of R lenses I've diddled with, they didn't seem to interfere with anything.

 

For the A-1 here's a link to a list of lenses not to mount: http://www.canonfd.com/a1inst/p78.htm

 

The same site has other Canon FD info.

 

Cheers,

<a href="http://www.cameraquest.com/canonflx.htm">Here is a link to Stephen Gandys site; explaining about possible problems when using the R lenses on later FL and FD cameras .</a><BR><BR>My pro neighbor had a Canonflex about 1960. The camera feels real solid. It has a funky bottom wind; which doesnt work when the camera body is on big tripods. If the tripod head is medium sized; it will work. <BR><BR>I believe that the "later" fully auto diaphram R mount lenses can be mounted to the "newer" FL and FD bodies; but the diaphram will not close down; except when on the older R series bodies. The R mount uses 2 pins; and the FL/FD use 1 pin to control/STOP DOWN the aperture. Thus a Canon owner's R mount lenses got "semi obsoleted"; when the new FL series arrived in 1964. In contrast the autodiaphram of Nikons in 1959 still works the same today; (unlike the 1964 major redesign by Canon).<BR><BR>The Canon breech lock mount worked from 1959 to EOS; but the pin scheme caused auto diaphram R lenses to crash in price; when they were obsoleted by the newer 1964 FL mount.

-- Duane ; its either the R series wont stop down automatically; or maybe wont stop down at all on the FL and FD series; hopefully all this discussion will answer this old question; about an interesting time in Canons long good history.

Charles, that's an interesting tidbit about the reserved pin. Having the maximum aperture and the total f/stop range available would allow the camera to calculate the minimum aperture. That's a neat approach. Next question is, why wasn't it implemented?

I have experience with all three Canon mounts. In chronological order;

<p> R series. Super Canomatic lenses have two operating pins at the rear. The large protruding pin cocks the mechanism as the film is advanced. The small, nearly flush pin, releases the mechanism to stop down when the shutter is tripped and reopen as the mirror returns. If you remove a lens before advancing the film, the mechanism is not cocked and the lens will not operate if you remount it to the camera after the film has been advanced. You can cock the lens manually before remounting it. Canomatic lenses have an exterior lever for cocking the mechanism, R lenses are completely manual. These lenses do not operate automatically on FL and FD series cameras. Super-Canomatic lenses generally have two aperture rings. One for auto operation, one for manual operation. This allows marginally convenient operation on later cameras. Canon realized the limitations of this system and introduced the...

<p> FL series. These lenses have a single operating pin at the rear. Canon reversed the operating direction of this pin so new lenses could be used on R series cameras without damage to lens or camera. R series lenses can also be used on FL series bodies without damage. FL lenses have a depth of field preview system to allow using the lenses in "preset mode" on R series bodies. On most FL series lenses this is an unmarked black ring adjacent to the aperture ring. On later FL lenses, there is a ring adjacent to the breech lock ring marked A-M. Again, Canon found themselves behind the curve and in 1971 introduced the...

<p> FD series. These lenses have one diaphragm operating pin at the rear. It looks different but functions exactly as the pin on the FL lenses. These lenses operate on FL series cameras in the same manner as FL lenses. The other pins relate to coupling to the camera body for full aperture metering and auto-exposure operation. Most breech lock lenses have a "stop down lock" with a detent at the extreme of the stop down pin's travel or a small lever to lock it at that limit. Perhaps another nod to the past, this makes the diaphragm operation completely manual and allows for marginally convenient use on R series bodies. Still, some fumble fingered people found changing lenses difficult, so Canon introduced the...

<p> New FD series. Operating features same as FD series though stop down lock was eliminated. These work fine on FL series cameras. They mount just fine on R series cameras but are nearly useless as only the lens' maximum aperture can be used.

<p> Cautions!!! Don't mount the deep seating 19mm FL lens on any body that does not allow mirror lockup. You will damage the camera. The later, larger 19mm FL-R (Retrofocus) should be usable on most Canon manual focus SLRs. Don't mount the deep seating 38mm FL-P (Pellix/Pancake)lens on anything other than a Pellix or mirror lockup body. You will damage the camera.

<p> Canon A series camera instruction books caution against using certain FL and R series lenses on A series cameras. I am not sure why. Some FL and R lenses have a stepped rear surface that may interfere with the f-stop setting lever or max aperture coupling pin in the cameras body. Perhaps someone else can fill us in on that.

Bill; thanks for the interesting history on Canon lenses.

I am replying to this old post because of some information I have on FL lenses. Casual Collector says he is not sure why some L lenses should not be used on A-1 or AE-1 camera bodies. The reason is that the rear of these lenses protrudes farther into the camera body and hit the aperture control lever in the body. For that reason many FL lenses can also not be used on adapters made for mirrorless cameras. A solution for most mirrorless adapters is to unscrew the aperture pin in the adapter that is attached to the "Close (or "Lock") - Open" ring on the adapter. Once removed the FL lens will fit in the adapter. This will cause a light leak so just replace the pin with a short screw or some other plug. The lenses that have this issue are: FL 19mm f3.5; FL 58mm f1.2; R 58mm f1.2; R 100mm f3.5 and the FLP 38mm f2.8

FWIW, here is a report on the

Canon FD 35-70mm f/4 AF - Canon's first SLR AF lens

Here is a photo of the three lens mounts, R (50mm f:1.8 Super-Canonmatic), FL (50mm f:1.8), and FD (300mm f:5.6 SC). As Casualcollector states, the FL is the simplest, with only one pin, versus the R and FD, with two pins each.