Archived posting to the Leica Users Group, 1996/06/10

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To: leica-users@mejac.palo-alto.ca.us
Subject: Re: CL-lenses
From: Reinhard Atzbach <r.atzbach@wiesbaden.netsurf.de>
Date: Tue, 11 Jun 1996 00:58:24 +0200
References: <199606102140.XAA11417@mailbox.swip.net>

Hallo Hans,
lets try to explain difficuilt things in my very restricted English.

> I will not argue aginst your findings, but here is what the 1989 Leica
> Catalogue said:
> Leica: General Catalogue for Photographic Dealers (1989), page 11-9:
> "...These lenses can be mounted on the Leica M, but do not provide precise
> copupling with the rangefinder. .....we do not recommend the use of Cl
> lences on Leica M cameras."
> 
> What does "precise coupling with the rangefinder" mean, really? If Garys
> conclusion is correct, focusing an Elmar C 90/4,0 should be less demanding
> for the M-rangefinder than a Summicron 90/2,0, and yet, Leica do not
> recommend it?!?

When You look into a Leica bayonet, you see a little wheel on a lever in 
it, just on top, beneath the rangefinder. It is this wheel, which turnes 
the prism of the rangefinder around. When you turn the meter-ring of the 
lens out, putting it to a near destination, the wheel comes out, at 
infinity the lever with the wheel is put inside.
I think the way length of the lever between infinity and 70 cm 
correllates with the way of a 50 mm-lens. Wide-angle-lenses have shorter 
ways, tele-lenses have longer. So then Leitz-people had to translate the 
individual adjustment-way of each lens into the constant way of the 
rangefinder-lever. In the M-series they did it with an additional ring, 
whose way is translated from the ring you draw around focusing and which 
presses the little wheel always exactly from the front. In the CL-Lenses 
they drive the wheel with the inner side of the ring you use for 
focusing. Of course this inner side can not be plain, it has to be 
curved. So the little wheel is not pressed exactly from the front like 
in the M-lenses. It is pressed from the side, so its going not so easy 
as it could be. 

But I don`t think, that this simplified construction must cause worse 
accuracy. The Leica manual, you are quoting from, with is from the good 
old times of Leitz Wetzlar. Please compare with my minilux: Manual focus 
on this camera has only 10 steps between 70 cm and infinity, and the 
Leica people tell me in the manual that this is enough ;-)

Regards
Reinhard


In reply to: Message from Hans Pahlen <hans.pahlen@mark.komvux.se> (CL-lenses)