Archived posting to the Leica Users Group, 2000/11/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]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