Archived posting to the Leica Users Group, 1996/07/20

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To: leica-users@mejac.palo-alto.ca.us
Subject: Re: Baseline length in M cameras.
From: Cameras <Cameras@ix.netcom.com>
Date: Sat, 20 Jul 1996 19:04:46 -0700
References: <1.5.4.16.19960720174449.24d73426@mailhost.primenet.com>

Ok guys, there seems to be some confusion about terms.

ALL M cameras, except the M1,  have a Rangefinder Baselength of 68.5 mm.
This is the distance between the two rangefinder windows.

M cameras differ in the finder magnfication.  The M3 magnification is .9, or
almost lifesize.   With some practice, most people can shoot the M3 with
both eyes open by holding the camera up to the right eye and keeping the
left eye open.  Try it.  

The M2/M4/M4-2/M4-P/M5/M6 all have the viewfinder magnification of .72.  

Multiplying the Viewfinder magnification times the baselength gives the
effective baselength.     If I remember correctly,  the M6J has a
magnfication of .8 or thereabouts--higher than the M2 etc but lower than the
M3.

But that is not all.   Leica claims that the split image factor in their M
cameras, ie the coming together of the image at the EDGES of the RF square
signficantly increases focusing accurately over the co-incendence of images
alone...about 30% if I am remembering correctly the specs I read years ago.
If you are not sure of what I am referring to, compare a M series RF image
to an earlier Screw mount RF/Canon RF or Nikon RF. 

Stephen Gandy

In reply to: Message from "Roger L. Beamon" <beamon@primenet.com> (Re: Baseline length in M cameras. Was RE: 90 mm Leica lenses.)