Archived posting to the Leica Users Group, 2008/12/13

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Subject: [Leica] M8 upgrade - 90 Cron APO focusing problems now Question????
From: len-001 at (Leonard Taupier)
Date: Sat Dec 13 13:47:31 2008
References: <> <BLU121-DS3010D2ED63D287290714FD4F60@phx.gbl>


Actually it is true. Because of the back focus issues I had with my  
M8 I decided to test 11 lenses for DOF first with a film camera, then  
with an M8, (actually two M8s). Every one of the 11 lenses showed the  
center of the DOF shifted to the back when going from film to sensor.  
The shift was greatest with the faster lenses and also with the more  
telephoto lenses. In a couple cases the DOF shifted enough so the  
point where I focused was either at the very edge or outside of the  
DOF. The worst lens was the Noctilux followed by the 50 Summilux Asph  
followed by the 75 Summilux. I found the most accurate focus was with  
lenses built in the 50s, like the 50mm Summicrons and even the 1.5  
Summarit. My 90mm AA was fine. But every Leica lens I have tested has  
a focus shift when going from film to digital. The shift with 8 of  
the 11 lenses was acceptable.


On Dec 13, 2008, at 2:09 PM, Aram Langhans wrote:

> Question.  I am not an M user, but am curious.  How can this be?   
> How can a
> lens focus properly on a film camera but not on the digital M?  If  
> this
> happened with every lens, I could understand that - something out  
> of whack
> with the camera.  But if other lenses that worked on a film camera  
> also work
> on the digital M, why would one lens behave this way?
> Aram, the curious R user.
>> Date: Sat, 13 Dec 2008 12:27:41 +0800
>> From: H&ECummer <>
>> Subject: [Leica] M8 upgrade - 90 Cron APO focusing problems
>> To:
>> Message-ID: <>
>> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes
>> Hello Luggers,
>> I have been having a dialogue with Schmidt (the local Leica
>> distributor) about getting my 90mm Summicron APO to focus properly on
>> my M8. Despite adjustments to the lens it still back focuses wide  
>> open
>> in the close range.
>> Trying another tact I decided to go for the M8 upgrade to the
>> viewfinder, and that led in a cascade to the new shutter upgrade and
>> in a what the hell attitude I also opted for the scratch resistant
>> LCD. I now have the camera back and my 90 Cron is no better matched
>> than before the upgrade and adjustment. Lux lenses focus fine as
>> before.
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In reply to: Message from leicar at (Aram Langhans) ([Leica] M8 upgrade - 90 Cron APO focusing problems now Question????)