Re: [Leica] DOF notches

[nbwatson@juno.com (N. B. Watson)]

The DOF marks (later M3 finders, all M2 finders) indicate the DOF of a
50mm lens at f5.6 (narrow notch) and f16 (wide notch).  With the rfdr
pre-focussed on any given point, simply place the rdfr patch over any
other subject nearer or farther away without re-focussing the lens. 
Separation of the two rdfr images by a margin falling within the width of
the notch (whichever is appropriate to your chosen f-stop which has to be
5.6 or 16) indicates that this subject would be with the "plane of
acceptible un-sharpness" we call DOF.  Again, it works accurately only
for those two apertures and only with a 50mm lens.  As clever as it is,
the DOF scales on the lenses have always been my guage of choice, even
with the M2 and "notches".  BTW, can anyone out there elighten me as to
how those folks who use the Contax G determine DOF?  I had the chance to
handle one belonging to a chap I met on holiday a while back (he was a
casual happysnapper who didn't know what DOF was) and noted straight away
that the lenses had no DOF scales nor was there any viewfinder aid.  My
impression was that it was less a point-and-shoot than a point-and-pray. 
Did I miss something?

Regards,
Nigel
On Sat, 10 Oct 1998 10:59:12 -0700 (PDT) M3novie@webtv.net (Scott Green)
writes:
>Hey folks!  So here's a question that I've been occasionally trying to
>figure out for some time now:  I once read somewhere that the little
>notches in the upper and lower egdes of the M3 viewfinder are supposed
>to be a quick DOF reference when using  a 50mm and -- what was it -- a
>90mm lens.  I haven't quite figured out how to use 'em, though.
>Granted, it's been a while since I last looked in there and tried.  
>Now
>that I've written this, I'll probably go and figure it out as soon as 
>i
>pick up the thing 8-}  So, are you supposed to look _between_ the two
>notches' edges, or between the two notches themselves?  It runs in my
>mind that I saw this in Brian Bower's book, but he wasn't very clear 
>on
>exactly what they do.
>
>Anybody out there able to clue in a dolt?  Thanks a lot!!
>Scott
>
>

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