Archived posting to the Leica Users Group, 2003/02/14

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Subject: Re: [Leica] Re: Hexar RF Back focus one more time
From: "Jacques Bilinski & Barbara Bradbury" <jbilin@axionet.com>
Date: Fri, 14 Feb 2003 09:30:44 -0800
References: <200302131714.JAA11678@mejac.palo-alto.ca.us> <a05111700ba71d2acb52f@[218.102.82.212]> <00fb01c2d3d8$e7153a80$6f01a8c0@jsbigrig>

> I'm sure this has been covered but why would you test a lenses/bodys focus
> using a wide angle @ infinity? Wouldn't you want to use a tele @ the
minimum
> focusing distance ???????????????????????????????????????????
>

You want to do the test at infinity rather than a close focus distance in
order to test the lens/body compatibility independantly of the rangefinder
adjustments. Rangefinders in RF cameras easily get out of adjustment if the
camera is banged, and this won't play a part in the test if you do it at
infinity.

You want the widest aperature lens you have in order to minimise the depth
of focus (i.e. depth of field inside the camera at the film plane).

Focal length doesn't matter, contarary to what is often written on this
list.  Best lens for this test is a Noctlux.

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Replies: Reply from Henning Wulff <henningw@archiphoto.com> (Re: [Leica] Re: Hexar RF Back focus one more time)
In reply to: Message from Cummer <cummer@netvigator.com> ([Leica] Re: Hexar RF Back focus one more time)
Message from "John Straus" <Mail@SlideOne.com> (Re: [Leica] Re: Hexar RF Back focus one more time)