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Re: [OM] rangefinder resolution

Subject: Re: [OM] rangefinder resolution
From: *- DORIS FANG -* <sfsttj@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 11 Feb 1999 22:27:02 -0500 (EST)

On Thu, 11 Feb 1999, William Sommerwerck wrote:

> to quote Douglas Adams: "This is, of course, impossible."

   What's Douglas' expertise in photography ? :-)

<William goes on to say this is all impossible, and that Doris F
must be joking> (she isn't). 
>  A resolution of .01" at 3' is better than one part in
> a thousand!

> A rangefinder would have to have a VERY long effective baselength to
> provide .01" resolution. Such resolution isn't needed anyway, because
> it's much greater than the minimum depth of field of any lens.

  The M6 does.

  Dear William ---
                    From the Editors at Photo Techniques:
                         [Sept/Oct 1998, p. 28]

" The human eye can detect differences less than .06 MILLIMETERS,*
 at three meters. That is less than the thickness of a human hair.
The virtual distance with which we look at the rangefinder spot in
the camera is +/- 1.4 meters (-0.6 diopter). We then are able to see
differences of 0.05 mm. As the rangefinder is built with a 1/100mm
tolerance, we may safely state that the accuracy of the rangefinder 
exceeds by a factor of five the one needed for the visual acuity of the
eye. "
    Thanks for making me re-read this fascinating article.

To paraphrase your sig...

> "Think, people, think!" -- Lex Luthor, "Superman -- the Motion Picture"

                             *= Doris Fang =*

Ps.* 1mm = .039" .06 x .039" = .00234 ", a lot less than .01"


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