Kibo informs me that (Dave Martindale) stated that:

writes:

It's easy. You'll need a tripod, positioned with the camera as parallel
as possible with the screen, & a shutter speed that's an *exact*
multiple of the displays refresh rate to prevent dark bars appearing in
the photo. Eg: to photograph an American TV screen (60Hz field rate,
30Hz refresh rate), you'd use a shutter speed of 1/30th, 1/15th, etc.

Mechanical shutters are just not that accurate on their own. Some
high-end video cameras have electronic shutters that can be adjusted to
almost exactly match a computer monitor, so there's only a very fine
dark or light line left moving up or down the screen, but still camera's
can't get exposures that accurate.

The above method's worked fine for me, every time I've tried it.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
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