Re: [Leica] M rangefinder focusing techniques

["Logan Reinwood" <reinwood007@hotmail.com>]

You should look at a M3 manual, in the latest M3 and M2 there was some help 
for DOF preview at f5.6 and f16 for 50mm lens (the RF zone was not a 
rectangle but somethin like:

__,---,__
!         !
!         !
!---,_,---!

This should give you an idea of how accurate you have to adjust the RF 
depending on the f stop you use and the DOF implied.

look at: http://www.fortunecity.se/jarlkullen/jarnekskogen/105/m3manual.htm
on page 9.

BR,

logan

>From: "Mxsmanic" <mxsmanic@hotmail.com>
>Reply-To: leica-users@mejac.palo-alto.ca.us
>To: "Leica Mailing List" <leica-users@mejac.palo-alto.ca.us>
>Subject: [Leica] M rangefinder focusing techniques
>Date: Mon, 30 Jul 2001 14:38:16 +0200
>
>I notice that when focusing my M6, I spend about thirty seconds checking 
>and
>double-checking to make absolutely sure that the two little images in the
>rangefinder are perfectly aligned.  I'm pretty sure that this is overkill, 
>but I
>don't know how much accuracy is really necessary.  I'd like to know from 
>those
>who have much longer experience with the M body just what sort of technique 
>you
>use for focusing so that something is indeed in focus without having to 
>spent
>two minutes verifying things.  I presume that there is some point at which
>"close enough" is identical to "perfectly lined up," but how do I know 
>reliably
>where that is?  Rules of thumb or similar suggestions for speeding up the
>process are most welcome.  I've tried checking the DOF indications, but 
>that
>takes as long as my attempts to get things perfectly aligned, so that 
>doesn't
>seem to work very well.
>
>For example, when focusing at something 200 feet away, I note that the 
>focus
>point isn't really at infinity, but in fact is very, very slightly short of
>infinity, but I'm never quite sure if I should try to make the adjustment.
>
>It's different from an SLR, in which the image is as sharp as it looks.  In 
>a
>rangefinder, the focusing is extraordinarily accurate for shorter focal 
>lengths,
>and apparently a large discrepancy in the rangefinder may correspond to a
>virtually infinitesimal difference in the actual focus plane of the lens.  
>Not
>knowing how close I _really_ am to acceptable focus gives me enough of a 
>complex
>that I miss some shots while I try to see if those two images are 
>_perfectly_
>aligned.


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