Archived posting to the Leica Users Group, 2000/11/10

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Subject: Re: [Leica] mechanical shutters
From: "A.H.SCHMIDT" <horsts@primus.com.au>
Date: Fri, 10 Nov 2000 21:13:26 +1100
References: <B62F599A.90FF%howard.390@osu.edu> <3A0A9FB3.1462B8C8@primus.com.au> <3A0BA5C4.4F7E45F9@yahoo.com>

Javier Perez wrote:

> Hi Horst
> I think even the best small value caps
> can eventually die out. Most I believe are
> epoxy encapsulated and epoxy though
> very good for this app is not compleatly
> inpermeable indefinitely. I think only glass
> could do that. I'm talking  in terms of serveral
> centuries. A metal blade FP mechanical shutter
> like that used on the R6 or S2 could easily last that long
> in normal use so long as the materials don't fatigue.
> I guess it's a contest between the chemical deterioration of electronic components
> and the fatigueing of mechanical components. The electronic
> shutter has both components but is very simple mechanically while the
> mechanical shutter is very complicated by comparison. I think the
> Industrial engineers invented the MTBF concept just for this sort of thing.
> I guess they would award the higher value to the electronic shutter and
> to the camera with a compleatly solid state metering system.
>
> See Ya
> Javier
>
> PS: It just ocurred to me. We still don't know the failure rate of silicon
> or MOS based devices past the first 50 years or so.
> So all our ideas on electronic reliability could be out the window.
>
> "A.H.SCHMIDT" wrote:
>
> > Martin Howard wrote:
> >
> > > Javier Perez jotted down the following:
> > >
> > > > There's only one type of electronic component that can  reasonably be expected
> > > > to deteriorate in an electronically timed shutter. It's the capacitor or
> > > > capacitors that govern speed as a function of discharge rate.
> > >
> > > Oh really?  What about the integrated circuits that have been popular in
> > > cameras with electronically timed shutters for the past 25 odd years?
> > >
> > > M.
> > >
> >
> >   Javier. these days the timing capacitors don't deteriorate anymore. they either
> > use tantalum, or plastic insulated capacitors. Even electrolytic capacitors, which
> > are not normally used, because of the large initial tolerance, don't deteriorate
> > anymore.
> >
> > Regards, Horst Schmidt

Javier, I am pleased to hear, that you talk about a few centuries for the capacitors to
deteriorate. For a moment there, I was worried they may only last another 80 or 80
years.
Now I decided to keep my beloved Pentax Super-A and don't have to try and sell it in a
hurry. Phew, what a relief.

Regards, Horst Schmidt

In reply to: Message from Martin Howard <howard.390@osu.edu> (Re: [Leica] mechanical shutters)
Message from "A.H.SCHMIDT" <horsts@primus.com.au> (Re: [Leica] mechanical shutters)
Message from Javier Perez <summarex@yahoo.com> (Re: [Leica] mechanical shutters)