I bought a used M6 TTL and tried my CV lenses on. What I noticed is the Leica meter is 2 stops off with these (CV LTM 50/1.5 and 35/2.5) lenses compare to the meter on my old R. I checked the ISO setting and it was both set to the same value. I swap the battery and it gave the the same results. Did I do anything wrong? I read the manual and the manual says Leica has a white spot on the curtain and its TTL meters that spot. While in R and other Rangefinders the meter meaters on the curtain, which is 18% gray. Is that the reason? I doubt about it very much. If they are using different metering patter, a 2 stop difference is quite unreal. on a white wall indoor at night, my R (with the same lens) gives f4 1/15, the leica says it is f4 1/60. I have been using my R with slides and I know it is pretty accurate. Help please.