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Re: [OM] OM SPECS

Subject: Re: [OM] OM SPECS
From: Kennedy <rkm@xxxxxxxxxxxx>
Date: Sat, 13 Jun 1998 13:40:04 +0100
In article , John Hermanson <omtech@xxxxxxxxx> wrote
>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.
>
>John
>Camtech
>
Yes, fill the frame with the TV screen and photograph it a couple of
times at each speed with bright image.

The developed film will only show part of the TV screen for shutter
exposures of greater than 1/60sec.  Select one of these that has the top
and bottom parts of the correctly exposed area within the TV frame and
then count the number of TV lines that are exposed.  Each TV scan line
is exactly 63.55uS (NTSC) or 64uS (PAL).  If you have fractions of a
line, don't put more than 10% accuracy on them because you can't see the
amount of horizontal overscan and thus take account of the horizontal
blanking.

This works best if you can get hold of an old B/W TV set, since the
shadow mask of the colour TVs makes it more difficult to count the lines
- that's probably why it isn't recommended much these days. 
-- 
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's pissed.
Python Philosophers         (replace 'nospam' with 'kennedym' when replying)

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