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

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Subject: Re: [Leica] Re: DR-SUMMICRON - with strange aperture scale
From: "B. D. Colen" <bdcolen@earthlink.net>
Date: Wed, 28 Nov 2001 15:36:29 -0500
References: <42.1e21447f.2936a29f@aol.com>

Seth - This is actually one of the more interesting bits of Leica trivia 
posted in some time.

Thanks

B. D.

SthRosner@aol.com wrote:

> In a message dated 11/28/01 11:10:08 AM Eastern Standard Time, 
> eric.calderwood@btinternet.com writes:
> 
> 
>>I have this DR-Summicron which has its aperture scale and index directly
>> > opposite to the distance scale. When mounted on the camera, the distance
>> > index is facing up and the aperture index and scale is facing down.
>> > 
>> > Is there a way to rectify this?
>> > 
>> > Dan K,
>>
> 
> Dan:
> 
> All of the DR and Rigid Summicrons were matched to individual focussing 
> mounts when delivered new from the factory. The likelihood is that your 
> Summicron lens head - the front optical part of your lens - has been mated to 
> a different focussing mount than the one originally furnished with the lens 
> when new. All DR Summicrons had (and have) an exact focal length of 51.9 mm. 
> The Rigid Summicrons produced at the same time had exact foacl lengths that 
> may have been 51.9 but that could have varied with an indivual specimen.
> 
> Unscrew the lenshead from your DR and look for two digits inscribed on the 
> blackened back part of the barrel. If your lens was really a DR at birth, the 
> digits must be "19". Leitz dropped the first digit, i.e. 51.9 = 19. 
> 
> The digits could be anything from 99 (meaning that with the dropped digit, 
> that lens would have an exact focal length of 49.9mm) or 23 (meaning that the 
> focal length is 52.3). I'm not stating limits at either end, simply giving 
> examples.
> 
> It is entirely possible that you have a Rigid Summicron lens head of a focal 
> length other than 51.9 and that someone has improperly mated it to a DR 
> focussing mount. Or it may be the correct 51.9 but the lens head has not been 
> properly calibrated to the focussing mount. That would not have happened at 
> the factory.
> 
> Alternatively, if the lens head is 51.9mm, it is possible that the original 
> focussing mount was damaged and someone found a replacement that has not been 
> properly adjusted.
> 
> My Rigid 50/2 Summicron happens to be 51.9mm. Last year, I contacted Don 
> Goldberg of DAG to ask if he might have a DR focussing mount I could use with 
> the Rigid lens head. He sent me one (since it was a DR focussing mount, it's 
> automatically 51.9). It turned out that when screwing the lens head in, the 
> aperture scale was off about 90 degrees to the left of top dead center, 
> making it awkward to use. Don said he could adjust the lens head to work, but 
> that meant that when used on the Rigid focussing mount, the aperture scale 
> would be off 90 degrees in the other direction. I had to send it back.
> 
> Sorry this has been so long but if you're not familiar with the lenses,  it 
> needs careful explanation. Good luck.
> 
> Seth      La k9 
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> 
> 


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In reply to: Message from SthRosner@aol.com (Re: [Leica] Re: DR-SUMMICRON - with strange aperture scale)