Archived posting to the Leica Users Group, 1996/04/19

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To: leica-users@mejac.palo-alto.ca.us
Subject: Re: M6 metering (again)
From: Thomas Knoles <tgk@mwa.org>
Date: Fri, 19 Apr 1996 15:30:05 -0400 (EDT)


Hello all,

I'll take a crack at this too, although I apologize if this has
already been covered in too much detail.  I receive this list as a
digest and am sometimes a little behind the curve...

Eastland's _M Compendium_, which I think is otherwise an excellent
book, contains a serious error in its discussion of M6 metering. He
says that changing the framelines will actually change the area
metered, which of course isn't true, since what is metered is
always the area of the 12mm white spot on the shutter curtain.  What
changes on an M6 is the size of the area _in the viewfinder_ which
is metered, and this depends on the focal length of the lens used. 
A 35mm lens will allow a larger portion of what is in the
viewfinder to be metered than, say, a 90mm lens, even though in
both cases the white spot covers the same 13% (or whatever the
actual percentage is) circle in the center of the frame. In practice, if 
you are metering a black cat ten feet away from you in the snow, the cat 
will fill a smaller percentage of the area metered with a 35mm lens than 
with a 90mm lens.  And you'd better think about compensating either way! 

By changing to framelines that are 50% higher (50 for 35, 75
for 50, etc.) you get a simply get a rough approximation of the part of the
image that is being metered.

Or does this confuse things even more?

Tom Knoles
tgk@mwa.org



Replies: Reply from Wolfgang Sachse <sachse@msc.cornell.edu> (Re: M6 metering (again)...)