Projector Speeds
vite
was due to the projector speed being increased to 25 frames a second rather
than the normal 24.
The theatre management needed to squeeze a special event in!
How much tolerance is there in projector speeds before the audio or the
visual is affected?
Alan Quick
CP__J
>
> For Television systems that run at 25 fps, it is standard to transfer
> films at that speed rather than the complex method used to convert 24 fps
> film to 30 fps NTSC. The advent of digital processing that can alter the
> pitch of the sound while the speed is still faster than normal now makes
> the 25 fps transfers sound much more natural.
Anyone familiar with, and sensitive to, the music will note a 4% speedup
immediately.
PAL's two Achilles' heels are (1) the speedup for theatrical movies and
US-filmed TV shows, and (2) excess flicker from the 50Hz refresh rate.
C.
Lincoln Spector
"vite" <quic...@yahoo.com> wrote in message
news:u6mcnRRTNN_...@brightview.com...
> Just seen Gangs of New York and I discovered that the shortened running
time
> was due to the projector speed being increased to 25 frames a second
rather
> than the normal 24.
> The theatre management needed to squeeze a special event in!
Lincoln
RICHVINCE
>was due to the projector speed being increased to 25 frames a second rather
>than the normal 24.
>The theatre management needed to squeeze a special event in!
How did you determine that the film was sped up 1 frame per second?
Rich
Richard May
I thought speeding up projection speed to get the movie over earlier
went out with silents. Where was this?
DM
vite
The cinema concerned was the Arts Cambridge UK
I knew the sequential scheduled start times were a bit close and was
surprised at the finish time.
The General Manager was prompted to assure me that I had seen all the film
as released as the editing was such that I was not sure whose cut I had
seen.
"Richard May" <rpm...@aol.com> wrote in message
news:3e2b69fb.0301...@posting.google.com...
William Hooper
And how was it done?
Kinoton electronic intermittent projectors have variable speeds, but
otherwise installations in first-run houses don't have control over
motor speeds.
Allan Young
>
> PAL's two Achilles' heels are (1) the speedup for theatrical movies and
> US-filmed TV shows, and (2) excess flicker from the 50Hz refresh rate.
>
>
>
>
>
>
> C.
Well at least it's better than having 20 Achilles' heels a la NTSC !
RICHVINCE
>as released as the editing was such that I was not sure whose cut I had
>seen.
Did the General Manager tell you they sped it up?
Both speeding up a film and editing it on site to shorten it are highly
improbable, if not impossible to do.
Rich
Mat Overton
> > US-filmed TV shows, and (2) excess flicker from the 50Hz refresh rate.
> >
I'd be surprised if you can really have that much control over a standard
cinema projector. Never seen any adjustments on a Westrex, or AFAIK a
Cinemeccanica, so I certainly wouldn't have thought it was common on other
makes.
Scott Dorsey
You can... uhh.. wrap masking tape around the motor pulley... uhh...
on some certain belt drive projectors that would remain nameless...
to increase the operating speed slightly. Not that I would know anyone
who has done this.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Scott Norwood
In article <29baf469.0301...@posting.google.com>,
William Hooper <w...@mindless.com> wrote:
>
>And how was it done?
>Kinoton electronic intermittent projectors have variable speeds, but
>otherwise installations in first-run houses don't have control over
>motor speeds.
I'd be interested in this, too.
I've only run one booth that had variable speed capability; they have a
pair of Simplexes, each of which has a frequency converter to allow them
to run at variable speed. This is at a local college, not a commercial
theatre, however.
--
Scott Norwood: snor...@nyx.net, snor...@redballoon.net
Cool Home Page: http://www.redballoon.net/
Lame Quote: Penguins? In Snack Canyon?
Martin
could be adjusted for silent films. I imagine the same technique could be
used in any commercial cinema (can't imagine why). A one fps adjustment
however sounds a bit too precise and does set of BS alarms.
> I've only run one booth that had variable speed capability; they have a
> pair of Simplexes, each of which has a frequency converter to allow them
> to run at variable speed. This is at a local college, not a commercial
> theatre, however.
>
> --
> Scott Norwood: snor...@nyx.net, snor...@redballoon.net
> Cool Home Page: http://www.redballoon.net/
> Lame Quote: Penguins? In Snack Canyon?
--
Martin McCaffery
Capri Theatre
Montgomery, AL
RBPerrine
speed for sound figuring out the motor speed based on 60HZ motors.....and in
Europe where they use 50HZ.....they chose 25 frames.....don't remember how this
all came about.....but the 25frame speed matched up with the television scan
rates.
If you look in the RCA 1040 manual at the gearing available....there are 50HZ
gears and also 60HZ gears.....(1938 manual)
The gears have different numbers of teeth on them to change the speed.
We had one theater here that had Simplex XL modified 35/70mm
machines.....orginally built as a straight 35mm then modified to run 70mm
also.....they were built for the UK and later shipped back here the US....they
were equipt to run at 25frames.....and when installed here they didn't bother
to change them.
Most of the shoudheads....Simplex SH1000, Simplex XL, RCA series....all have
50HZ gearing available for them.
They will run 25 frames.
SGuttag
improbable, if not impossible to do.
Rich
>>
While editing on site has gone out since changeovers have not been the norm
(managers once upon a time would direct an operator to make a changeover early
to get out early...a very dispicable thing).
Projectors, however, can often easily be changed in speed. Nowadays,
projectors like those from Kinoton (and others) use frequency converter units
with 3-phase motors...the speed is set on the converter. Kinoton supplies all
of their current projectors such that they can play at 24 or 25 fps. I
generally reset the 25fps speed in the US to 18fps so it is obvious that the
wrong speed has been selected and it instantly becomes the generic silent
speed.
Steve
SGuttag
Kinoton electronic intermittent projectors have variable speeds, but
otherwise installations in first-run houses don't have control over
motor speeds. >>
Kinoton mechanical intermittent projectors have a 25fps speed switch too...even
the lowly PK-60D has a toggle switch in the rear (inside of the projector ) to
choose 24 or 25fps.
SG
SGuttag
could be adjusted for silent films. I imagine the same technique could be
used in any commercial cinema (can't imagine why). A one fps adjustment
however sounds a bit too precise and does set of BS alarms. >>
The AFI in DC variable speed system is a little more complex that a simple
rheostat but yes they too can run variable speed for silent films.
SG
nsa*lenoir
>Sorry Guys......somewhere along the line....in the USA they chose 24 frame
>speed for sound figuring out the motor speed based on 60HZ motors.....and in
>Europe where they use 50HZ.....they chose 25 frames.....don't remember how this
>all came about.....but the 25frame speed matched up with the television scan
>rates.
Absolutely not. Projectors in european movie theatres are running
24fps. Even if some modern theatres, equiped with Kinoton system,
CAN run at 25fps also. But because of the 50 Hz electrical system in
Europe the TV system runs at 25 fps, including telecine for video.
That is why a movie with a running time of 100 minutes in theatres
has a running time of 96 minutes on Tv or video.
User2002
The international standard for theaters is 24 fps. When constant speed
motors were used on projectors, the gear sets were different for 50 or 60 Hz
because the motors ran 17% slower on 50 Hz. They still do! Isn't physics
wonderful!
Film shot for televison in Europe is often shot at 25 fps so that the
showtime and sound are technically accurate.
Films shown on televison in many parts of europe that were shot at 24 fps,
are projected to telecine at 25 fps, and management makes round shoulders if
you tell them it is not strictly Kosher. If anyone objects, he can turn his
TV off.
Many, but not all, projectors now use a 3 phase syncronous motor. These are
connected to a variable frequency drive, that usually runs on single phase
power. Most cineplex models do not allow the operator to vary the speed.
What for? How often does vintage silent or a film shot for European TV come
along?
New projectors are in the pipe that can change the pull down on the fly.
Trailers could be shot 2 perf, and the show be four perf on a single
platter. Saves a bit of rawstock, and allows for more trailer in the same
space. If the audience knows there is 20 minutes of trailer, more people
will rush the popcorn stand!
The motion picture printer known as a Model C, also uses a different size
pulley for 50 Hz regions. Most people don't bother to change the speed when
used equipment is shipped across 50/60 Hz boundries. But, then Europe tends
to run 17% slower in any event, :)
Daniel Haude
User2002 <no...@supplied.com> wrote
in Msg. <3cYY9.2$zC...@nwrddc01.gnilink.net>
| Many, but not all, projectors now use a 3 phase syncronous motor.
I've only seen asynchronous 3 phase motors on projectors. Increasingly
they're hooked up to variable-frequency drives because since they've
become so cheap that's now the standard way of handling three-phase
motors.
--Daniel
--
"With me is nothing wrong! And with you?" (from r.a.m.p)
Daniel Haude
nsa*lenoir <*nsa*len...@skynet.be> wrote
in Msg. <v7v73v416u832pq34...@4ax.com>
| But because of the 50 Hz electrical system in
| Europe the TV system runs at 25 fps, including telecine for video.
In priciple you're correct but it should be noted that this is an entirely
historical reason (i.e., nowadays there is no need for the TV fps to have
anything to do with the AC line frequency).
Scott Dorsey
>On Sun, 26 Jan 2003 16:26:42 +0100,
> nsa*lenoir <*nsa*len...@skynet.be> wrote
> in Msg. <v7v73v416u832pq34...@4ax.com>
>
>| But because of the 50 Hz electrical system in
>| Europe the TV system runs at 25 fps, including telecine for video.
>
>In priciple you're correct but it should be noted that this is an entirely
>historical reason (i.e., nowadays there is no need for the TV fps to have
>anything to do with the AC line frequency).
No, there still is. The idea here was that if there was induced hum, it
would be much less irritating if the rates were the same, because the hum
bars would be static rather than constantly moving.
Admittedly in this day of regulated supplies, hum problems are much less
of an issue.
And, when the TV frame rate was shifted from 30 to 29.94 fps in 1954
when color was grafted onto the American standard, we got moving hum bars
back again anyway.