OK - Leica history lesson on the levers...
Here's my 1950s Leica M3 - the camera that killed off the Japanese pro rangefinders and pushed them into SLRs. (Which Asahi had started making even before the M3.)
There are 3 levers on the front. The small one below the shutter release is the rewind lever, which Leica used instead of a button. The large lever below that on the left side of the picture is the self timer lever. Not all of the M series had the self timer, such as some of the M2s as lower-cost Leicas. The lever on the right of the photo below the viewfinder window is the frame preview lever. The M3 had frames for 50, 90, and 135mm lenses only. The M2 had frames for 35, 50, and 90mm lenses. The M4 had all 4 frames, by showing the 35 and 135mm frames at the same time.
When they made the M6 with built-in meter, the meter battery was placed where the self timer was on the earlier models, so these clock-work self timers were discontinued.
Many of the Pentax film cameras had a self-timer lever below the shutter release in about the same position as the Leica, such as the MX and LX. Sometimes it also worked as a DOF preview lever when pushed towards the lens.
The Canon FT also had a dual purpose self-timer / stop-down lever at this position, that originally also turned on the meter as the lens stopped down. That was a very convenient position, as your 2nd finger on the right hand rested right next to this lever: just push it towards the lens and it stopped down and metered. I wish the K-5 had that "FT" style control, as it was much easier to work.
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