Archived posting to the Leica Users Group, 2003/02/23

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Subject: Re: [Leica] RE: Longevity of Leica products
From: John Collier <jbcollier@shaw.ca>
Date: Sun, 23 Feb 2003 09:43:51 -0700

Can you do TTL flash on a analog circuit that will fit into an M body?

John Collier

On Sunday, February 23, 2003, at 09:04 AM, Austin Franklin wrote:

> Javier,
>
>> I think the M6,7 etc are all analog!
>
> The M6 is all analog, no doubt, but the M6 I'm reasonably sure they 
> have
> some simple digital circuitry in it.  At least that's how I would do 
> it.
>
> How do you time the shutter in an analog system?  Somehow, you have to
> measure time, to a pretty precise measure.  It's a LOT easier to do by
> counting clock pulses...which would mean digital.
>
>> It's cheaper to build a non-emulative analog circuit
>
> I disagree.  Analog circuitry used for timing would have to be 
> calibrated,
> and is very susceptible to drift and temperature.  Digital circuits for
> timing are highly reliable, and maintain the "count" over their 
> temperature
> range with exceptional accuracy.  The only downside to digital 
> circuitry is
> it's susceptible to low temperatures.
>
> I will ask Leica on Monday if the M7 circuitry is all analog or has any
> digital.  I'd like to know.

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