Archived posting to the Leica Users Group, 1999/10/07

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Subject: Re: [Leica] (M) Flash Synchro
From: Godfrey DiGiorgi <ramarren@bayarea.net>
Date: Thu, 7 Oct 1999 01:40:01 -0700

>> Maybe Leica should commit some reversed engineering in regard to the
>> Nikon FM2 shutter? Yes, it's bigger, but hey... no one said life was
>> going to be easy.
>
>Yup,  that's what I want, a Leica M that sounds like trash can
>lids clattering in an alley when I trip the shutter!  But, hey,
>it would flash sync at 1/250.

Most of the noise you hear from the FM2n is from the mirror mechanism, 
the aperture stop down mechanism, and the mirror auto return mechanism. 
The shutter itself, while not as quiet as the Leica M shutter, is not 
that much noisier. It could be made significantly quieter with some 
attention to noise control details.

>What would it take to raise the
>sync speed to, say, 1/90 or 1/100?  If it requires more noise,
>I'm agin it.

To execute a flash sync at 1/80 second with acceptable shutter response 
time with a horizontally operating focal plane shutter, you must open the 
first curtain and traverse the film gate in less than 12ms, hold the gate 
fully open for about 1-1.5 ms, and then close the second shutter in less 
than 12ms. This takes higher spring pressures, lighter curtains and more 
effective damping mechanism that is currently used on the Leica M 
shutter. Nikon achieves it on the F3 with titanium curtains and 
electronic shutter timing. 

A vertically traveling shutter has an inherent advantage in that the 
distance the shutter must travel is 1/3 less, but the acceleration and 
deceleration of the curtains is necessarily greater which requires more 
sophisticated curtain braking and damping control, and greater stress on 
the curtains. Noise control is more difficult although the modern, state 
of the art shutters used in today's Contax SLRs are amazingly quiet, even 
including the mirror and aperture mechanisms' operation. 

There's no reason that a state of the art shutter could not be designed 
for the Leica M body, and it would not change the camera one iota from 
the perspective of the user except for the loss of the mechanical timing 
escapement mechanism noise at slow speeds. It would not be trivial, I 
grant you that, as design and tooling all need to be taken into account, 
but it's certainly possible to do it.

Godfrey