Archived posting to the Leica Users Group, 2003/01/14

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Subject: RE: [Leica] Useful link for focus adjustment
From: "Austin Franklin" <darkroom@ix.netcom.com>
Date: Tue, 14 Jan 2003 13:40:23 -0500

Hi Herb,

> I absolutely don't understand Martin Tai's geometry.  He claims that
> if the subjects eye is 100 cm from the camera as indicated by the
> scale on the lens barrel and is in the center of the image, that if
> the camera is rotated so that the eye is now at the edge of the
> frame, it's distance will have been reduced to 94.7 cm.  This looks
> like utter nonsense.  Can anyone prove it to be correct?

Well, it is utter nonsense depending on how you "turn" the camera.  It
certainly doesn't move 5.3cm, or more than TWO inches if it's turned
"axially" about the center of the film plane.  If you put it on a tripod,
using the tripod socket that is on the EXTREME end of the camera bottom,
you'll get possibly an inch...  It would appear to me that unless you really
turn the camera deliberately foolishly, you just can't get 2" of deflection.

Austin

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