Archived posting to the Leica Users Group, 2001/04/17

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Subject: RE: [Leica] RE: Was Medium format camera (now pit-bull arena)
From: "Austin Franklin" <darkroom@ix.netcom.com>
Date: Tue, 17 Apr 2001 19:08:02 -0400

> The bottom line, concurrent with Marc's summary. None of this matters one
> iota. And if it did, you would not own a Leica M, Hasselblad 500
> series, LF
> lens with shutter, etc.

Which Leica M lenses have lenses with shutters?

I'd be curious if you happen to have the acceleration curves and/or the
open/close times for any leaf shutters?  That would certainly substantiate
or refute the claim that it doesn't matter.  My understanding that this
phenomenon does matter is apparently standard knowledge, and has been
discussed extensively on the Rollei and LF lists.

> As a sidebar, I have an R4sP when tested by Ernst Hartmann, showed 100%
> shutter accuracy from 1sec to 1/1000th.

It is almost impossible to accurately measure a leaf shutter at high speed,
with reasonable tolerance, without some very exotic equipment.  In order to
accurately measure a leaf shutter at high speed, you would have to measure
intensity assigning some threshold for 'open', or somehow measure only at
the edge.  Do you happen to know what equipment he used to make these
measurements?

The claim "100% accuracy" has me curious too...since I've tested hundreds of
shutters, I've never seen one "100% accurate" at even one speed.  The are
always off by some small percentage, and of course, it depends on how much
precision your measuring equipment has.

I don't want to get into a pissing contest with you, so don't make it one.
I would like you to substantiate your claims.  I don't care if you're right
or wrong, but if you are right, I'd really like to understand why, because
there are many people I know who claim just the opposite...and some of them
are professional optical engineers.