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Re: [OM] leaf shutters

Subject: Re: [OM] leaf shutters
From: Moose <olymoose@xxxxxxxxxxxxx>
Date: Tue, 20 May 2003 12:32:59 -0700
Bill Pearce wrote:

I have no doubt that those shutters can make the top speed on the bench,
just after adjustment. What I do doubt it that they cam maintain that speed
a year later. I remember when one of the photo magazines did speed
measurements as a part of their camera tests, and had trouble finding a
horizontal FP shutter that could make more that about 1/800 top speed.

Well, I'm sure our resident professional shutter adjusters will know more about this.

I find it incredible that you can fling mechanical bits around, accelerating
and braking in a matter of milliseconds, without self destruction.

The shutter curtains in a focal plane shutter move no faster at 1/2000 sec than at 1 sec. Only the timing between the start of the first curtain across the film and the start of the second changes. The only theoretical limit to speed is the slit width. When it becomes really narrow, there are several practical problems. Some that occur to me off the top of my head are: Diffraction through the slit will have optical consequences. Small degrees of unsquareness in the edges of the curtains can give uneven exposure. Small variations in the timing of shutter release and linearity of travel become more critical.

Moose



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