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Re: [Phys-l] 240 and 600 Hz

70mm is of course twice 35 in width, but there is also the height to
consider in the cost. I think the proposal may have been for conventional
35mm which would only double the film cost. I don't think that all theaters
could handle 70mm. Only the upscale ones would probably handle it, and the
bulk of pictures were still in 35mm. Some theaters even used 16mm.

70mm was used for some of the very big budget spectacular films especially
in super wide screeen. They also used special lenses to make the image
wider, so I don't know off hand whether 70mm ate up 4x the film, or less
than that. According to a friend the reel size for 70mm was enormous, so I
suspect the 4x figure would be accurate. I have only been a projectionist
for 16mm, so I have not handled the bigger film sizes. I could earn a small
amount of money and get to see a good film by being a projectionist. I
already knew how to use a B&H projector which was complicated, but
considered to be the Cadillac of school projectors.

I would presume the double speed would give smoother motion with less
perceptible grain. I don't think it would do much for the sound because the
sound technology was not that good. It reputedly did look a lot better.

If you look at the current ATSC standard for HD TV it is very open with
provisions for all possible frame rates 23.97, 29.98, 24, 25, 30... and a
variety of resolutions. Indeed one of the commonly used resolutions 720x480
is not even in the standard, but apparently there is a provision for extra
specs outside the standard. So I am not sure that 120 is necessary to get
an exact 25Hz frame rate, but it may make it easier.

It just occurred to me that one of the advantages of a higher refresh rate
is that they have a screen with lower persistence which would make less
smearing possible. I don't think it is the refresh rate which raises the
cost much, but the lower persistence may be a bigger cost factor. The move
from 60 to 120Hz apparently does buy a better picture, but 120 to 240 is
somewhat marginal, and may only be noticeable by a few people. I think
120Hz is now probably standard except for very small screen sizes.

John M. Clement
Houston, TX

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf
Of Bernard Cleyet
Sent: Monday, April 18, 2011 8:56 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] 240 and 600 Hz


On 2011, Apr 18, , at 10:05, John Clement wrote:

Actually the double frame
rate would have been a change in the gearing of the
existing projectors,
which was very possible to do without huge expense. And it
would probably
have been cheaper than the 70mm films which ate up huge
amounts of expensive
film stock.

John M. Clement
Houston, TX


Same film cost, and less projector cost, no?

Would the perception be the same? 70mm: 4X "pixels" (note
the ""); double speed sgrt. "noise reduction"?

So 70 mm better?

bc
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