Archived posting to the Leica Users Group, 2010/02/24

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Subject: [Leica] how to test focus
From: hopsternew at gmail.com (Geoff Hopkinson)
Date: Thu, 25 Feb 2010 08:00:48 +1000
References: <C7A9E2B6.2C8EE%chris@chriscrawfordphoto.com> <alpine.BSF.2.00.1002241117210.34698@shell2.crowhost.com>

Ken it has parallax correction. Keeping in mind that the frame-lines are
approximate coverage, the view finder frame lines position will always be
adjusted as the focus distance change. The focal length doesn't matter. You
need a lens fitted of course. Keep the camera still and turn the focus ring
to the minimum. You will see the frame-lines move towards the bottom right
hand corner as the compensation works.
I don't think tht you will be able to determine anything useful from your
proposed experiment regarding focus accuracy.
Cheers
Geoff
http://www.pbase.com/hoppyman


On 25 February 2010 03:24, Ken <kkanno at users.symmetric.net> wrote:

>
>
> On Tue, 23 Feb 2010, Chris Crawford wrote:
>
> What is adjusted depends on what is off. The lens could be off or the body
>> could be off, or they could both be wrong! Also, the lens has two things
>> to
>> adjust, the accuracy of the cam that pushes against the RF follower in the
>> body, and the shimming of the optics to correct focus. The body has three
>> things that can be off: The distance between the lensmount and the film
>> plane, the infinity setting of the rangefinder, and the close-distance
>> setting of the rangefinder!
>>
>
> Interesting. I didn't know there were so many places adjustments could be
> made. I think I'm just going to cut and grind a piece of glass and see what
> it shows. It will be easier than waiting for film to come back.
>
> The m7 seems to have parallax correction, but does anybody know how far off
> the rangerfinder box can be off from the center of a lense itself, or is
> this always lined up correctly on a 35 or 50mm lense?
>
>
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In reply to: Message from chris at chriscrawfordphoto.com (Chris Crawford) ([Leica] how to test focus)
Message from kkanno at users.symmetric.net (Ken) ([Leica] how to test focus)