Archived posting to the Leica Users Group, 1996/11/23
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At 08:44 AM 23/06/96 +0200, you wrote:
<SNIP>
>The obvious solution to this problem (M7?) is a continuously variable
>exposure time simulator, as used by many other camera manafacturers.
>Physical damage will not result from setting intermediate speeds.
>
>Gerard Captijn,
>Geneva,
Great idea, Gerard, but regrettably, continuously variable reistors suffer
two problems that individual resistors do not. First of all, they get
"dirty" from oxidation, and have to be cleaned every 4 or 5 years. Second,
and more importantly, as they are in the process of oxidizing, they slowly
shift their values for any given position. Fixed resistors (assuming gold -
not silver -contacts in the switch) will remain absolutely reliable for a
*very* long time.
In a stereo (my trade), the variable resisitor used for the volume control
presents no problem until it makes a "static" type noise when turned.
That's the oxidation in it's final stages. Prior to that, as the value
changes, you just adjust the control to the level you want, without worrying
whether that was where it was set 6 months ago for the same volume. Meters,
however, are a bit more critical.
I vote for Leica's choice of fixed resistors.
Hope this helps.
- -----------
David Young | No electrons were hurt
Victoria, B.C. CANADA | in the creation of
youngs@IslandNet.com | this message.