Re: [Leica] Leica Users digest V11 #33

[Doug Herr <Telyt@compuserve.com>]

>>>
I would like to see the incorporation a focusing assist LED. Certainly the
technology is available for what would amount to a partial autofocus
system.
The sensor for the focus detection would work through the lens in parallel
with the exposure meter. This system would function without the motors and
accompanying weight, cost, mount/lens redesign, and aesthetic changes that
a
full-fledged auto-focus system would demand. This focus-assist system would
ideally run in parallel with the range finder focusing system currently
used
in the M6 (and could be ignored).
<<<

IMHO this would add significant complexity in (what would become) the
mirror box area.  In order to work through the lens, the AF sensor would
need to be AT THE FILM PLANE, not near it as the painted metering spot is,
and as far as I know the only way to do this aside from moving the shutter
and film out of the way is to incorporate a moving or semi-silvered mirror
that would reflect the light from the central (I presume) image area to the
floor or roof of the mirror box.  The mirror would have to flip out of the
way, or would cause light losses if semi-silvered and stationary.  If it's
not a semi-silvered mirror the metering would also require some new
arrangement because the mirror would block the light that reflects off the
painted spot.

In essence this would add the vibration and shutter lag of the SLR to a
superb instrument for a marginal gain in utility.  Does anyone want a
mirror flopping around inside his/her M6?  I wouldn't.

Doug Herr
Sacramento
http://ourworld.compuserve.com/homepages/telyt