Re: [Leica] Leica CL 40mm Summicron on other M-mount cameras

[Henning Wulff <henningw@archiphoto.com>]

At 8:27 AM -0700 3/6/02, John Collier wrote:
>Hi Mark,
>
>It is very simple to check. Mount lens, set it to infinity and point the
>camera at something very far away. If it all lines up, great. If not, it
>still may be within the DOF of the lens. Yes, I have seen a 40/2 mounted on
>several M bodies and on one it lined up correctly at infinity but not with
>the other two. The DOF of the 40/2 probably would have taken up the slack. I
>guess it all depends on how fussy you are and how often you are focused
>close and wide open.
>
>Many people have said that Leica made it all up to keep people from buying
>the cheaper 40/2. The lads in Germany may be too fussy for our tastes but
>they are right about the differences in lens cam design.
>
>As I said earlier, try it and see.
>
>John Collier
>
>
>
>>  From: Mark Langer <mlanger@ccs.carleton.ca>
>>
>>  Is this true according to your direct experience, or just from what you've
>>  heard?  I'm asking you this because last weekend I had a discussion with
>>  Reinhold Mueller on this very subject, and he answered 
>>unequivocally that the
>>  incompatibility of the 40mm
>>  Summicron with other M cameras was just a myth.  I'm fond of the 40mm focal
>>  length (I've got an Olympus 40mm f2.8 in LTM and just got a Rollei 
>>35 SE) and
>>  have been considering buying the 40mm Summicron for a M6.
>>
>>>  From: John Collier <jbcollier@powersurfr.com>
>>>
>>>
>>>  The answer is: a CL lens may focus correctly on a M camera...or it may not.
>>>  The CL uses a very steep lens cam and the horizontal position of the CL's
>>>  rangefinder roller is critical. The M lens cam is not steep and horizontal
>>>  position of the rangefinder roller is not critical. In fact, on the M
>>>  camera, the length of the rangefinder arm (horizontal position) is
>>>  adjustable to fine tune focusing accuracy. So it is not unusual to have the
>>>  rangefinder roller in slightly different horizontal positions on 
>>>different M
>>>  cameras.
>>>
>>>  So the short story is that a CL lens may line up properly at 
>>>infinity on one
>  >> M camera and may not on another. Try it and see.
>>>

Actually, the problem is not usually that the infinity position is 
off, but that the infinity position is on and closer distances are 
off. I saw this in two M5's, including one I had, in the 70's. 
(Haven't touched a CL or CLE lens since then). Because the geometry 
is different, the rate of change of the lens extension is not matched 
correctly by the arm movement in the focussing mechanism. You have to 
check by first making sure that the infinity position is on, and then 
take a picture of something on a wall from 30 to 45 degrees off the 
wall at a distance of 1.5m or so with the lens wide open. If that is 
on, then your camera/lens combo is OK.

Using M lenses on the CL/CLE should be fine, as long as the focussing 
accuracy is sufficient, and you can see around the lens :-).

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    *            Henning J. Wulff
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