Hmmm, interesting. Never thought of it that way. I was simply measuring how
long light
fell on a small photodetector and calling it the 'shutter speed.' I never
considered it
may be different on one side or the other, but obviously the moving curtains
caould
cause that to be true. Thanks for the explanation, John.
george
John Hermanson wrote:
> 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
> plane
> is commonly overexposing, because the curtain speeds are simply not being
> used
> correctly.
> To be truly accurate, a shutter tester must also measure curtain speeds.
>
> John
> Cmatech
> http://www.zuiko.com
>
> 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
> >
> >
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|