Archived posting to the Leica Users Group, 2001/11/28

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Subject: [Leica] Re: DR-SUMMICRON - with strange aperture scale
From: SthRosner@aol.com
Date: Wed, 28 Nov 2001 17:41:45 EST

Dan:

I wish I knew. I've not seen that before. I will make a guess but remember it 
is pure guess: the 39 was on the lens at birth, meaning 53.9 (although I 
don't recall ever seeing a number that high). Then the lens was rebuilt, 
perhaps in order to be a dual range, and became 51.9 N(ew)? Just conjecture. 
Can't figure out what else it might be. The fact that the second set of 
numbers is of a differrent size makes me wary that it may not have been the 
factory that did it.

I also wonder if you have noticed any problems with focus? If the lens head 
is misfitted, your photographs should be somewhat out-of-focus.

John Collier is correct though: you need to have the lens examined by a 
really competent repair facility that knows what it is doing to regularize 
whatever is going on with your lens. Incidentally, what is the serial number? 

There were two changes in the DR/Rigid Summicrons: the coating was changed on 
the later lenses and improved to enhance contrast. And the focussing mount 
was also changed. The first series has the grooves that are cut into the 
focussing ring on the outer raised surfaces of the ring; with the later 
lenses, the grooves are cut into the indented scallops of the ring. I'm not 
sure that the changes took place simultaneously not what were the serial 
numbers at which changes occurred.
There has always been some conjecture that the optical formula of the lenases 
was also changed. I have correspondence with both Wetzlar and Solms that 
confirms that the actual optical design - apart from the coating modification 
- - didn't change throughout the production run, 1956-1970.  

Because your result with the numbers and this response might be interesting 
to LUG readers, this technologically challenged LUGGER is going to try to 
forward both.

Best,  Seth           LaK 9  
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Replies: Reply from Dan Cardish <dcardish@sympatico.ca> (Re: [Leica] Re: DR-SUMMICRON - with strange aperture scale)
Reply from David Rodgers <drodgers@swiftnet.com> (Re: [Leica] Re: DR-SUMMICRON - with strange aperture scale)
Reply from Feliciano di Giorgio <feli@d2.com> (Re: [Leica] Re: DR-SUMMICRON - with strange aperture scale)