Archived posting to the Leica Users Group, 1997/02/24

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Subject: Ques. about Elamar 90/4 LTM
From: karabog@Hydro.CAM.ORG (Bogdan KARASEK)
Date: Mon, 24 Feb 1997 22:06:40 -0500 (EST)

Hi,
I just bought an Elmar 90/4,LTM, sn 15456, and I wanted to ask a few
questions about it.  Would anybody know when it was manufactured.  I assume
that the lens is uncoated but when it is put under a light, I can count six
reflections; the 2 top ones have a very light purplish tinge to them and the
penultimate one has a slight bluish tinge to it.  Are the colours due to a
coating or to some sort of optical phenomenon?  Why do I see six reflections
in the lens; is it because there are 6 pieces of glass in the lens?

Other questions:

The f stops are numbered as follows: 4/4.5/6.3/9/12.5/18/25/36.  How do they
relate to modern f stops?

The top third of the barrel, containg the glass and aperture blades,
unscrews from the bottom 2/3 of the barrel.  This part is hollow and
contains the focusing ring.  Does this capacity to unscrew the glass from
the rest of the barrel serve some function?  I was thinking that maybe one
could screw the glass part unto a shorter or longer barrel in order to get a
different focal length?  As an alternative, I was thinking that the glass
part with the aperture blades could be used as an enlarger lens.  The only
problem would be that the lens thread has a diameter of 33mm. as opposed to
25 or 39mm.

This or any other information about this lens would be very appreciated.
Thanks!


  Regards
         
         Bogdan KARASEK 
         karabog@cam.org
         Montreal
         Quebec
         CANADA