Archived posting to the Leica Users Group, 2001/02/10

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Subject: Re: [Leica] focus inaccuracies: my test results
From: Martin Howard <howard.390@osu.edu>
Date: Sat, 10 Feb 2001 16:12:23 -0500

Christer Almqvist jotted down the following:

> I have always found the method you use to determine if the camera
> focuses correctly (i.e. taking pictures of a ruler at 45 degrees
> angle) gives results that are difficult to interpret.
> 
> In my opinion it is better to draw a thick vertical line on a  sheet
> of paper  and stick the paper to the wall. [rest snipped]

Essentially, you're both doing the same thing.  With the receeding ruler,
you need to do the trig to figure out the true subject-to-film distance
(since your basically photographing the hypotenuse of a triangle) which
ultimately will probably result in a more accurate result than trying to
figure out what exactly 1/16" is in terms of turning the lens barrel.

M.

- -- 
Martin Howard                | It never ceases to amaze me how people con-
Visiting Scholar, CSEL, OSU  | sistently pay more attention to *how* you
email: howard.390@osu.edu    | say something, than *what* you say.  (Anon)
www: http://mvhoward.i.am/   +--------------------------------------------