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Rom vs Cam


williesheldon

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As a general rule, single cam lenses will work only with the original Leicaflex

 

2 cam lenses work with that camera and the SL and SL2 (although I was able to mount one on an R8 recently, and it seemed to be OK in Manual or Aperture Priority only)

 

3 cam lenses work with any Leica reflex

 

R cam (or 3rd cam) lenses will only work on cameras from the R3 on

 

ROM is similar to 3rd cam in that they will only work on the R3 or later, but have additional electronic contacts for use with the R8, R9 and DMR

 

I'm sure there will be a few exceptions to this, but will leave that to those with more in-depth knowledge. :)

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LeicaRCam-01wtmk.jpg

 

LeicaR-Cam3.jpg

 

 

There are some series variations in Leica R-Mount lenses:

  • One-cam (Original Leicaflex). This is the silver-chrome triangular cam marked (1) on the photograph right. Leica doesn't recommend using 1-cam or 2-cam lenses on the R8 or R9.
  • Two-cam (Leicaflex SL/SL2). This is the silver-chrome triangular cam at the top-left (11 o'clock) position in Exhibit A (behind the 3rd cam in the Exhibit B). Leica doesn't recommend using 1-cam or 2-cam lenses on the R8 or R9 because the cam may damage the ROM contacts if it's out of spec.
  • Three-cam (Leica R series). The 'R-cam' or third cam is the stepped black metal cam barely visible in Exhibit A, right next to the silver wedge-shaped 2nd cam. The third or R-cam is used on R-series cameras (R3-R7). Three-cam lenses are the most compatible as they can be used on any Leica SLR ever made. In response to my lousy photo, reader Ken O'Kelley sent me a much better photo (Exhibit B) of the 3rd cam.
  • R-only (Leica R series only). These lenses only have the stepped R-cam and cannot be used on the older Leicaflex cameras. Leica changed the mount slightly so they will not even mount on a Leicaflex. You need to make sure that you can see cams 1 and 2 if you want to use newerlenses on older bodies.
  • ROM lenses: the latest lenses designed for use with the Leica R8 and R9 cameras which had electronic contacts between the camera body and lens. This allows the lens to transmit additional data to the camera. ROM lenses cannot be used on the original Leicaflex series as they will not even mount due to a slight bayonet change. They have the R-cam so they can be used on any R series Leica

05-ELMARIT-R-19-MM-F2.8-ROM-PHOTO-3.jpg

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They even can add the ROM contacts to an Cam3 lens. It costs about 220 euro.

 

True, they can, but you then lose the 3cam functionality, i.e. you can no longer use such a lens on any Leicaflex body.

 

Andy

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As TimF mentioned, there are exceptions. Some 2-cam and 3-cam lenses will not mount on the Leicaflex Standard or Leicaflex SL because of a slight change in the flange, to prevent interference between these few lenses and the mirror box. These lenses are intended for the Leicaflex SL2 and (for the 3-cam models) later R bodies.

 

Originally the SL2-spec lenses were Minolta designs, the 16mm Fisheye, 24mm Elmarit, and 80-200mm f/4.5 (not to be confused with the much more recent 80-200mm f/4). Many later Leitz/Leica designs also used this Minolta-derived mirror clearance spec: 15mm Elmar/Elmarit, late 19mm Elmarit, 35mm Summilux, late 50mm Summilux, 21-35mm Vario, 35-70mm f/4 Vario, and probably the 28-90mm Vario. The 2x APO-Extender-R also uses the more restrictive mirror clearance specs.

 

Apart from the minolta-spec mirror box interference, the big reason ROM lenses cannot be used on Leicaflex bodies is because the camera body's cam follower for the first cam would damage the ROM contacts. The Leicaflex Standard and Leicaflex SL2 have this cam follower, not the Leicaflex SL, but because the Leicaflex and SL use the same mount flange specs, ROM lenses are made with the R flange to prevent damage from use on the Leicaflex or SL2.

 

With small and reversible changes to the lens and camera body, ROM lenses which do not have mirror box interference problems can be used on the SL: On the SL, the lens lock pin and the inner diameter of the flange are trimmed slightly to R specs (without the flange lug trim that would allow the minolta-spec lenses to fit) and on the lens the second cam is added. Result: the lens will still work as before on any R body, the SL will still work as before with 2-cam and 3-cam lenses, and the modified ROM lenses will fit and meter on the modified SL.

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