Help with 2/3-CAM R lenses on R8 and R6.2 : LUSENET : Leica Photography : One Thread

I have read the CAM 101 article but I am still confused as to whether 2 or 3 CAM lenses can be used on the R8 for fear that the CAMs will damage the ROM contacts on the R8 (see page 62 of the R8 instruction manual).

It seems that Leicaflex lenses cannot be used on the R8 so this would mean 1 CAM and 2 CAM lenses. But if that is the case, why are 3 CAM lenses usable on the R8 when they have the same 2 CAMs that the 3 CAM lenses have? Won't these damage the ROM contacts too? What does the 3rd CAM do? If I were to buy a 3 CAM lens, how do I use it on the R8 or the R6.2? Am I limited to using only the aperture priority mode? If so, do I have to always turn the lens' aperture to its widest aperture, check the exposure metering and then physically adjust the aperture and shutter speed manually (like an M6) to maintain the same EV? I am at a total loss here as I dare not mount a 3 CAM lens onto my R8 to experiment. Thanks for your help!

David Yeo

-- David Yeo (, September 25, 2001


The only cam you need is the third cam ("R" cam). On some R8 body/3 cam lens combinations, the first cam can lightly hit the ROM contacts on the R8 body. Over time this will damage the contacts. So the first time you try a 3 cam lens, check to see if it leaves a mark on the ROM contacts. If there is no mark, you can use that lens with confidence. The problem only occasionally occurs so most of the 3 cam lenses should be fine. Leica was just being cautious.


-- John Collier (, September 25, 2001.

David, the 3rd cam is the metering cam for the R bodies from R3 through R8. I've only used an R8 briefly but my 3-cam lenses all worked fine with the R8. You can use aperture-priority, shutter- priority and program modes without restriction. What the ROM contact do is to tell some flash units what focal length the lens is to zoom the flash head to the right coverage, and to fine-tune the exposure calculations in matrix metering mode. ROM lenses cannot be used on the old Leicaflex bodies because one of the cam followers that these bodies used will damage the ROM contacts. ROM lenses have a different bayonet mount than 3-cam lenses which prevent mounting a ROM lens on a Leicaflex body. Some people (myself included) think that using a 2-cam lens on any R body may eventually damage the body's cam follower because the 2nd cam contacts the cam follower with a significant longitudinal force while the follower was designed only for rotational forces. I may be overly paranoid about this because many other people report that they've had no problems using 2-cam lenses on R bodies. To be safe, use only 3-cam, 3rd-cam or ROM lenses.

-- Douglas Herr (, September 25, 2001.

Thanks for the respose. I am afraid I still don't understand why it is ok to use a 3-CAM lens on the R8 but not a 2-CAM since the 3-CAM lens essentially has the same 2 CAMs as the 2-CAM lens but only has this extra small black tab for the 3rd CAM? Won't the 2 chrome CAMs on the 3-CAM lens also damage the R8 contacts? Thanks.

-- David Yeo (, September 25, 2001.

You can mount and use 2-cam lenses on R bodies including the R8 without damage, and the auto diaphragm will operate properly. You can meter manually in stop-down mode using the DOF preview lever to stop the lens down to working aperture. On my R7 I have to subtract 1/2 stop at apertures other than wide open, with my 2-cam 50/2 which is the only 2-cam lens I own. I don't know why this is, evidently it has to do with the meter indexing mechanism.

What you *never* want to do is attempt mounting a 3rd-cam-only (or ROM, which also has only the 3rd cam) on an SL or SL2. Without the sloping SL (2nd) cam to push the body's meter arm safely out of harm's way, the 3rd cam alone will foul it.

-- Jay (, September 25, 2001.

>>> What you *never* want to do is attempt mounting a 3rd-cam-only (or ROM, which also has only the 3rd cam) on an SL or SL2. Without the sloping SL (2nd) cam to push the body's meter arm safely out of harm's way, the 3rd cam alone will foul it. <<<

That has not been my experience. I had a 3rd-cam 50mm Summicorn-R (since converted to 3-cam) that worked fine on my SL except since it did not have the SL metering cam I had to use stop-down metering. No damage.

-- Douglas Herr (, September 25, 2001.

I cannot even mount my 28mm ROM lens on my SL, it goes onto the bayonet, but does not turn. Trying to do so has not damaged the camera as far as I can see.

-- Robin Smith (, September 27, 2001.

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