[Leica] M6 Battery Current Consumption

[Harry Haige <haige@compuserve.com>]

At least on the "classic" M6, the "B" position does not really turn the
exposure meter circuit "off", it merely prevents it from being turned "on".
 There is no drain on the battery except while the LEDs are lit following a
depression of the shutter release, normally for 10-15 seconds, which period
can be terminated early by making the exposure or selecting "B".  Otherwise
the only thing selecting "B" does is prevent inadvertent actuation of the
shutter release and circuit in a camera bag, etc., as the circuit has no
quiescent or "standby" current consumption.  

Duracell for example rates their DL1/3N battery and D357 cell at about 160
mah, and with my M6's meter consumption of 10-12 ma, a lifetime of about 15
hours would be expected.  The M6 manual's figure of about 20 hours is
probably reasonable given tolerances in ratings and ability to operate with
some drop in voltage.  

I have no experience with the latest TTL cameras however.