Re: [Leica] Using 2 cam lenses on an R3

[Doug Herr <71247.3542@compuserve.com>]

On Wed, 10 Feb 1999, Alex Hurst wrote:

>Dan Post wrote:
>>I have the same model 50 Summicron, three cams with built in lens shade,
and
>>have no problem using it on my SL!
>>Is it possbile there might be some damage there?
>
>The lens flange looks perfect, and the mounts on the SL bodies show very
>little wear. It just seems a bit reluctant to fit in the throats of either
>of my SLs. Just tried again, and it definitely doesn't go on either.
>
>I obviously don't want to force it. The strange thing is that all the SL
>lenses mount very sweetly on the R3. I can't believe that Leitz got their
>flange tolerances wrong. Just to add to the mystery, the R lens _does_
>mount OK on the front end my 2x Extender R, the back end of which is
>specifically for Leicaflexes.
>
>S/N of this strange reluctant Canadian 50/2 Summicron R is 2824064. This
>wouldn't be one of the rare R  beasts where the mount is purposesly
>designed so it _can't_ be mounted on 'flexes? I seem to recall reading
>something about that somewhere, but it would only make sense for 3rd
>cam-only  lenses - whereas this is definitely 3-cam.

>BTW, I may have the solution to my own question about using 2 cams on R
>cameras. How about:
>
>1) Select a suitable shutter speed in manual mode.
>
>2) Stop-down the lens using the DOF preview lever until the meter needle
>coincides with the shutter speed selected.
>
>3) Release DOF lever and shoot.
>
>I don't think it can be used in program mode because that would require
the
>3rd cam to transmit the aperture information while the lens remains wide
>open.
>
>Could someone out there confirm this or correct me?
>
>TIA
>
>Slan
>
>Alex

My 50mm Summicron-R (Canadian w/ built-in hood) was originally a 3rd-cam
lens but even in that configuration it would fit on my SL and worked well
with stop-down metering (it's now a 3-cam lens).

OTOH the mount flange on my 14256 extension tube was originally R-only,
with a small ridge on the flange that prevented its use on the SL (it's now
SL-compatible w/ stop-down metering).  AFAIK there's no good reason the
14256 had to be made as R-only equipment.

Is it possible some previous owner put the R-only flange on your 3-cam
Summicron?

As for using 2-cam lenses on an R-body, I've heard from some people that
the metering lever in the camera hits the 2nd cam at exactly the right
point for accurate metering; OTOH the forces the cam exerts on the lever
(mostly axial) are not the ones the lever was designed for (tangential) and
may damage the lever over time.

I haven't used a 2-cam lens on my R4sP bodies but I have used a Viso lens
with 14127 (without the 3rd cam).  The 14127 doesn't have the 2nd cam, so
with this combination the body's metering lever doesn't reach the "nul"
position and metering is off by 1-1/2 stops.  My advice: get the 3rd cam
installed on the 2-cam lenses, and IMHO the mount flange of the 50 is
suspect.

Doug Herr
Sacramento