Timothy Normand Miller wrote:
On 4/21/07, Dieter <[EMAIL PROTECTED]> wrote:
I wonder why films can get away with 48 Hz, but CRTs are annoying at
70 Hz?
I think it has something to do with motion blur. A CCD takes very
little exposure for a frame, while film, I think, has a longer
exposure period. So you get more motion blur with film than with a
CCD. Also, there may be something to the way the TV scans the image,
while the film projector flashes it all at once. Note that I could be
totally full of crap here, so you may want to look elsewhere. There
are people who know the answer to this question.
A pro movie camera has a shutter speed adjustment. It is not totally
independent but rather a percent of twice the frame rate. So, at 24 fps
you might shoot action shots at ~1/200 of a second which would reduce
the blur considerably. This does have problems -- we have all seen the
wagon wheels turning backwards in westerns. :-)
So, I think that it is the nature of a scanned CRT that is the issue. I
don't really see flicker at 60 fps, but it bothers me. 70fps is OK for
me but I understand that others see it flicker. This is odd since the
CRT screen has some persistence and a movie screen has none.
--
JRT
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