While the Leica screw-mount and M bayonet
mount rangefinder lenses are familiar to most camera collectors, Leitz also produced a wide range of lenses for its single lens reflex cameras. These cameras have a long history, starting out with the original Leicaflex , the auto-exposure R3, the famous all-mechanical R6, and continuing on to the current Leica R9 which accommodates an 11-megapixel digital back.
With the exception of auto-focus, the Leica SLR system is just as advanced as their equivalents from Canon or Nikon. However, because Leica always stood for precision, ruggedness, reliability, and mechanical perfection above everything, they never went towards the lightweight plastics and looser focusing tolerances that auto-focus cameras entailed. Thus, all Leica R lenses are manual focus only. For the same reasons, Leica has not produced as many zoom lenses as its Japanese competitors. In fact, a couple of Leitz's SLR zooms are actually Minolta designs. Ask around, it's easy to find out which.
Leica R Lenses
For the most part, R lenses are interchangeable with any age Leica SLRs. Except for the newest ROM lenses which should not be used on Leicaflex cameras, at most you lose the ability to matrix meter, or to meter at full aperture (stop-down metering only).
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.
Upgrading older lenses / Using adapters
Although older lenses were originally made with 1- or 2-cams, Leica offered an upgrade service to bring them up to 3-cams (you can also modify a R-only or ROM-only lens backwards to 3-cam as well, although you lose the ROM contacts if you do this). So just because a lens has 3-cams doesn't mean that it is a second-generation lens. You have to use other factors in determining the lens version such as the distinct profile of each version, the serial number, the presence or absence of a built-in lens hood; or the weight.
Many people use their Leica R lenses on Canon SLRs (including digital SLRs such as the Canon EOS 20D) with an adapter that is widely available (see CameraQuest.com for a source in the USA). I use mine with the Hansa adapter which I bought in Japan (picture right). If you have an adapter, it does not matter if you have 1, 2, 3, or ROM cams on your R lens if you are using it on another camera system since you will always be shooting using open-aperture metering. The system works fantastically well. I have some photographs using the 180mm Elmarit on my gallery page.In order for an adapter to work, there are two factors. The first is the body "lens registration" distance or the distance from the lens mount to the film surface. The second is the mount "throat size" or the diameter of the mount. For an adapter to slip in between the body and lens of differing manufacturers, the registration distance of the lens must be greater than the registration distance of the body; and the throat-size of the lens must be smaller than the throat size of the body mount.