Archived posting to the Leica Users Group, 2007/09/01

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Subject: [Leica] Re: do it yourself back-focus adjustment..."
From: hoppyman at bigpond.net.au (G Hopkinson)
Date: Sat Sep 1 16:15:11 2007
References: <98A0D67D-CE25-48F3-84D2-A34BBA5BEC1C@mac.com><002001c7ec8b$e5295910$6400a8c0@corp.nortel.com> <5DDF2A59-8784-410E-9C7C-C56C8073DAB1@mac.com>

Guys can someone be explicit there regarding what you are correcting? Focus 
wide open at practical infinity or a close position?
Focus at a particular f stop?  Someone said that they are adjusting so that 
there is more apparent DOF in front than usual. Since
the acceptably sharp zone will always be deeper behind, I read this as 
actually moving the sharpest point forward.
There is a difference between a global back focus (lens adjustment error) 
and a focus shift visible near wide open as you stop down.

I can certainly understand that you may end up with an adjustment that works 
in practice for your own circumstance (lens and use),
I'm just really interested as it seems to me that you are introducing new 
errors, especially with other lenses for example. It may
be that DOF masks the error with other lenses. Just guessing, I imagine that 
Leica is checking/adjusting the individual lens focus
mechanism, which is not the same as adjusting the camera body roller arm 
naturally.

The inquiring Hoppy wants to know.

-----Original Message-----
Subject: [Leica] Re: do it yourself back-focus adjustment..."

Vick,

The original idea to do this came from the Leica Forum.  Look there  
if you want to find a more rigorous approach to the problem.

Bob

On Sep 1, 2007, at 4:33 AM, Vick Ko wrote:

> Okay, now I understand.
>
> You are adjusting the RF arm.  I anticipate that it only takes a  
> very very
> small amount of adjustment.  If the adjustment is large, then you  
> will end
> up affecting the infinity alignment of the RF image.
>
> Congratulations on discovering this method.
>
> regards
> Vick
>
> -----Original Message-----
> From: Robert Rose [mailto:robert.rose@mac.com]
> Sent: Saturday, September 01, 2007 2:33 AM
> To: Leica Users Group
> Cc: vick.ko@sympatico.ca; Leonard J Kapner
> Subject: do it yourself back-focus adjustment..."
>
> Vick,
>
> We had a thread on this around March or so.  I had posted some  
> samples and
> how to do it at:
>
> http://gallery.leica-users.org/v/rjrose/focus/
>
> Bob Rose
>


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Replies: Reply from len-1 at comcast.net (Leonard Taupier) ([Leica] Re: do it yourself back-focus adjustment...")
In reply to: Message from robert.rose at mac.com (Robert Rose) ([Leica] do it yourself back-focus adjustment...")
Message from vick.ko at sympatico.ca (Vick Ko) ([Leica] RE: do it yourself back-focus adjustment...")
Message from robert.rose at mac.com (Robert Rose) ([Leica] Re: do it yourself back-focus adjustment...")