[Leica] Metering anomaly on M6 TTL with Noctilux

["Simon Lamb" <simon@sclamb.com>]

I have noticed something strange with the metering on my M6 when using a
Noctilux.  In order to explain in as few words as possble I will use the
following symbols to show the symbols that are present in the viewfinder:  >
o <

I was intending to take a picture at f/1 and at 1/60 second the viewfinder
reading was  > o  (1/2 stop underexposure)
As I was at f/1 I set the shutter speed to 1/30 second and the viewfinder
reading was  o <  (1/2 stop overexposure, as you would expect)

I assumed that if I rotated the aperture ring to the 1/2 stop between f/1
and f/1.4 I would get a viewfinder reading of  o  (correct exposure), but
what I got was still  o <  (1/2 stop underexposure).

I has to set an aperture of f/1.4 before I got a viewfinder reading of  o
(correct exposure).

It appears that instead of f/1 at 1/60 second being the same as f/1.4 at
1/30 second it is actually an additional 1/2 stop.  This is not in general a
major issue as 1/2 stop in many cases is barely noticeable, but I wondered
if anyone else had noticed this happening.  However, I was using Scala
pushed to 400 and 800 and the 1/2 stop does make a difference.  I am using
an M6 .85 TTL with the Noctilux.

Simon