[Leica] Is the TE a zoom?

[henningw at archiphoto.com (Henning Wulff)]

At 9:54 PM -0500 2/3/08, Howard Ritter wrote:
>I'd forgotten that, but I'm not sure that means anything by itself, 
>since the lens diagram for the original TE (in my original post I 
>was mistakenly referring to the diagram for the WATE) appears to 
>show that the change in FL is produced by moving the front element 
>group alone, and that it occupies the extreme positions at the 
>extremes of focal length. If the change in FL is a direct function 
>of the displacement of the zooming element, then there is no reason 
>why the seemingly odd choice of mechanical FL selection excludes the 
>possibility of a zoom. I vaguely recall having read why this design 
>was chosen but I can't remember the reasoning. If this is correct, 
>then there should therefore be a functional (but unmarked) 35mm 
>position between the 28 and the 50. WIsh I had one to diddle with!
>
>--howard
>
>
>On Feb 3, 2008, at 3:13 PM, Henning Wulff wrote:
>
>>  At 6:07 PM +0000 2/3/08, Steve Unsworth wrote:
>>  It's even easy to tell the TE can't be a zoom because the order of 
>>focal lengths is: 28-50-35. Can't have a zoom with that arrangement.
>>
>>  --  *            Henning J. Wulff
>>   /|\      Wulff Photography & Design
>


Okay, the positions of the marked focal lengths does not absolutely 
preclude a true parfocal zoom design, but it would make the whole 
thing needlessly complex, to no advantage (to be redundant). Leica 
designers have never shown that they enjoy complexity in and of 
itself like the Contax designers, and that sort of layout if the lens 
were a zoom would be needlessly complex.

In any case, it's not a zoom. There is nothing useable between the 50 
and 28 setting; or, for that matter between 50 and 35. I have one 
(and a WATE) and the TE is not a zoom. The WATE is.

-- 
    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  /###\   mailto:henningw@archiphoto.com
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