Subject: Re: [OM] OM SPECS
From: John Hermanson <omtech@xxxxxxxxx>
Date: Mon, 15 Jun 1998 17:33:34 -0400
Some 4s 4Ts and 4Tis may have some shutter error at 1/2000, but that is affected
mostly be CURTAIN speeds, which  should be set first for accuracy, then speeds
should be checked.  All of the above models do not have this problem.
Some repair shops try to  set high speeds by turning the curtain speeds up and
down.  This may  give you a correct speed in the center of the frame, but on the
closing side of the frame, it is likely the curtain slit has closed and there 
may be
no exposure (especially at 2000).  The speed at the opening side of the film 
is commonly overexposing, because the curtain speeds are simply not  being used
To be truly accurate, a shutter tester must also measure curtain speeds.


gma wrote:

> Yes, I did this.  Homebrew shutter tester. Some ICs, crystal, 7-segment 
> displays
> and a photocell.  Works pretty good.  It told me that my OMs had very little
> shutter error (except the 4t at 1/2000 had a large error ( I can't remember 
> the
> numbers)).  But it also told me what I suspected ( and what prompted me to 
> build
> the thing in the first place): that my lenses for my Mamiya C-330 (all those
> lenses have leaf shutters built in) had LARGE error, sometimes up to 50%.
> george
> R. Lee Hawkins wrote:
> > In your message dated: Fri, 12 Jun 1998 10:28:00 MDT you write:
> > >>There used to be a way to check shutter speeds by taking pictures of your 
> > >>TV
> > >>screen.  There is no real home test for shutter speeds except maybe a 
> > >>$5000
> > >>shutter tester.
> > >
> > >Actually Calumet sells an electronic shutter tester for about $80 (or they
> > >did a few years ago)
> >
> > Yes, and you can easily make one from a surplus Commodore 64.  Or home
> > brew one from components if you are so inclined.
> >
> > Cheers,
> > --Lee
> >

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