MM Lenses on RTSII


New Member
I am new to the forum and new to Contax, and already have a question: I recently purchased an RTS II body and 3 lenses, 2.8/28MMJ, 2.8/45MMJ, and 1.7/50AEJ. I just had the body serviced by the local authorized shop, and have seen something interesting. The AE lens shows the proper f-stop in the viewfinder and the MM lenses are set at one stop higher than what is shown in the viewfinder consistently. I took the lenses in with the body and they are going to research it. The lenses on an RX body they had registered properly. I'm guessing this is a known issue, although everything I've read says that the MM lenses are compatible with the RTS bodies. I love the feel of the RTS II body and the viewfinder is great, and I could live with this if I had to make a compensation adjustment, for instance, but need to know where I am. A few rolls of film and I would know, but wanted to ask...

Please excuse me if this is a dumb question, but I've done a few searches and found nothing except that the lenses are backwardly compatible, no reference of issues. This seemed like a good place to find more depth of information...

Many thanks in advance, David


Well-Known Member
OK, let us start with the MM vs AE lenses. If you notice on your MM lenses the max aperture should be in Green. I recall in one of my lens manuals it was stated MM lenses should be used on bodies with T (time) or Shutter Speed priority; this was due to a lighter aperture blades used in construction. They of course can be used on AE (Aperture priority) bodies like the RTS II; backward compatible. The AE lenses though were not listed in any lens manual to be used on newer bodies on T mode, but they can be used on A mode; like with any AE body.

I have both lens and body types and follow these rules. Admittedly I have not attempted to use an AE lens in T mode because I almost always shot in AE mode. I don't find there are any quality differences between the two types of lenses, so I buy what costs lower. But if you are a T mode shooter definitely get the MM lenses.


Well-Known Member
Oops, I forgot to mention the other issue you're seeing. On the lenses, there is a L-shaped bracket with screws holding it to the lens body. It is used to adjust the aperture reading/readout on your body. On the Yashica lenses it is a milled out with the lens barrel so is in a fixed position where with the Contax lenses they could be adjusted. I had that issue once before which I've found that it can also be an issue with your body's index ring (fixed with a CLA with Kyocera when they still serviced Contax equipment). I hope this helps.