window backlighted scene

["Nicolas Levinton" <nicolev@jet.es>]

I recently shot 2 rolls of Kodak Tri-X 400 (Leica M6 + Summicron 50mm f/2)
at a nursing home. I took a lot of the pictures on two old women that were
sitting in a sofa chatting, at an angle of 0 degrees (I was just in front)
at a distance of about 3 meters from the women. 1 m. at the back of the
sofa there was a window with white curtains that throwed a lot of light,
although there were other windows to the sides. When I framed, I tried to
avoid the window, but the composition I chose, required a little portion of
it to be included.

I measured on the women and sofa, and with 1/60 my M6 suggested f/8. I did
as she said.
The problem I found afterwards, when I developed and shot the contact
sheets, is that in all of the pictures that correspond to the case I
mentioned and even other in which I was in an angle to the sofa( maybe 45
deg.) I got a zone right in the middle and middle-top of the frame with
about 1/2 stop more light(clearer in the positive).

My question, that I think that it could have something to do with my
habitude of having everything done automatically, and that I deal with now
that I changed to LEICA, is:

Why???? Is it something avoidable? Should I have used the lens-hood
included on the lens? Is it just my ignorance? Will the overexposed circle
disappear when I burn that zone in the darkroom? Or what?

Please help. 
thanks.


If Darwin was right, how is it possible
that after millions and millions of years
of evolution, humans are not born with 
a LEICA as one of their hands.
Nicolas Levinton, Madrid. SPAIN
      nicolev@jet.es