Archived posting to the Leica Users Group, 1999/12/17

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Subject: Re: LUGRe: [Leica] Focusing difficulties
From: Eric Welch <ewelch@neteze.com>
Date: Fri, 17 Dec 1999 21:47:53 -0800

sometime around 12/17/99 6:14 PM, Andrew M. Moore at moore@rscs.net was
heard  to write:

> Granted, the RF lets in almost all the light, while a typical fast lens
> on an SLR might be f/1.4, but f/1.4 is pretty bright viewing in an SLR.
> So what's the big deal?  Is focusing in a rangefinder patch really any
> different from the split-screen method in your typical SLR?
> 
> Oh boy.  Let the flame wars begin!  :)

You are asking for it here. :-)

The difference is you have the width of the lens front elemetn in an SLR,
pluse the design limitations of the screen in the SLR keeping it from
working with wide lenses. The rangefinder has a wider base (the reason there
is a window for the rangefider all the way over by the shutter release. The
wider the base, the more accurate the rangefinder. But at higher
magnifications (90mm and longer) you lose that advantage, and an SLR takes
over, becuase you can see the subject with a higher magnification than in
the M viewfider. It's rangefinder base plus magnification that makes
focusing accuracy.

But then the split image rangefinder in an SLR is pretty useless to begin
with. They're optimize for about 5.6, unless specifically optimized for
something else, like some screens for the Nikon F line.
- --

Eric Welch
Carlsbad, CA
http://www.neteze.com/ewelch

"You can't cajole someone into loving you by simply being nice to be
around." - Garrison Keillor - As heard on "A Prairie Home Companion"