Film-Tech Forum ARCHIVE: 24 FPS vs 25 FPS projection in today's theaters

This is topic 24 FPS vs 25 FPS projection in today's theaters in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Lionel Fouillen (Member # 1475) on 01-05-2004, 06:38 AM:

I'd like to know if you have an idea about the proportion of theaters today, that actually project films at 25 frames per second instead of 24.

Posted by Steve Kraus (Member # 476) on 01-05-2004, 09:46 AM:

None that I am aware of save those who have electronic drive projectors set wrong or incorrect timing pulleys and somehow, inexplicably, don't know it, and those who have worn out multi-V (driven) pulleys resulting in a faster than standard speed (I went through that once upon a time). Which rounds out to essentially none.

Posted by Stephen Furley (Member # 1277) on 01-05-2004, 10:35 AM:

Lionel, I'm not sure I understand the question; do you mean places that project all films at 25 fps, or places that can run at that speed, and therefore would do so If they received a film intended to be run at that speed, but run other films at 24?

In London, the National Film Theatre can run at variable speeds from 16 (I think) to 30. ICA Cinema 1 can run at set speeds of 18, 24 and 25. Both places normally run at 24, and would only do otherwise when required.

I don't know of any which normally run at 25. What about preview theatres in television production facilities in PAL areas, they may run at 25.

Didn't the Philips FP-20s with pulsed lamps run at 25 on 50Hz. supply? I don't know of any still in use now.

Posted by Lionel Fouillen (Member # 1475) on 01-05-2004, 03:17 PM:

Stephen,

I meant theaters purposedly showing all films at 25 FPS to slightly shorten the total projection time, therefore sparing the xenon lifetime, arguing that the difference between 24 and 25 is hardly noticeable, and arguing even more that "it's the way films are shown on TV anyway" (although all this seems unacceptable to me!)... [Wink]

Posted by Paul Linfesty (Member # 214) on 01-05-2004, 03:33 PM:

I always suspected the old AMC Stockdale 6 theatres in Bakersfield (1974-2000) did this. Every feature length film shown there seemed to get out a cuople of minutes short of the published running time.

Posted by Michael Schaffer (Member # 1204) on 01-05-2004, 04:33 PM:

Many Kinoton models have the option to run at 25fps. I know that a lot of people cannot resist the temptation, but in the chain I worked for in Germany, we made sure the projectors would always run at 24fps. Especially after one projectionist had set a machine to 25 to be able to go home earlier (as if those 3 minutes or so made a difference). The next day, we ran interlock and it led to an ugly accident.
A lot of cinemas in Eastern Europe have the Meo 5XB projector. This will only run at 25 because that was the standard in the Eastern Block.

Posted by Chris Hipp (Member # 1788) on 01-05-2004, 06:10 PM:

Is really worth the trouble to save about 6 minutes from a two hour movie?

Posted by Brian Guckian (Member # 1678) on 01-05-2004, 06:10 PM:

I hope the answer would be almost none. I think this has come up before - certainly projecting 24fps material at 25fps is unacceptable; the change in pitch in fact is noticeable to quite a lot of people for starters (which is corrected during TV transmission).

Like Stephen said, the 25fps option is for screening prints of TV productions in specialised preview theatres. Nowadays I would imagine this doesn't happen much, as DigiBeta + DLP seems to have made huge inroads in this area.

Where are those security covers!

Posted by Stephen Furley (Member # 1277) on 01-06-2004, 05:43 AM:

Lionel, I don't know of anywhere doing this, which is not to say that there isn't anywhere doing it, of course.

Posted by Dick Vaughan (Member # 540) on 01-06-2004, 07:35 AM:

There was a small 4 screen near here that ran at 25fps but of course never advertised it. When asked by the discerning patron why the film was shorter there than at any other cinema in the area they used to tell them it was so the projectionist could catch the last bus home! [Roll Eyes]

They were also renowned for forgetting to swing the anamorph when changing from ads and trailers to a scope feature on a regular basis.
[Mad]

Luckily the place is no more

Posted by Sam D. Chavez (Member # 1841) on 01-06-2004, 09:58 PM:

The Ziegfeld Theatre in NY had Zeiss projectors that would not run anything but 25 FPS. This led to no end of trouble but they may still be there for all I know.

Posted by Lindsay Morris (Member # 1430) on 01-07-2004, 02:20 AM:

It was quite common in AC (50hz) arc days to slightly increase the projector speed to avoid the strobing effect of the shutter and the AC arc pulsing.
The most common way was to simply wind some plastic insulation tape onto the drive motor pulley (in the direction so it was always winding on when running.. so it stayed there) and thus bring the projector speed up enough so the strobing was not evident. Who knows exactly what the speed actually was but it was faster than 24fps and did not seem to alter the pitch of the soundtrack much that I could ever notice.
There are a couple of AC arc private cinemas I know of that are using tape on the pulley and one owner intends to manufacture a couple of new pulleys so he does not have to worry about occasionally replacing the tape which slowly does wear down.
The change in pitch was quite evident if you had only done one machine and ran film and then on the change there was a slight pitch shift.
At one of the old cinemas where I worked years ago a rectifier failed during a show (each machine had it's own rectifier). The old RCA Arconomiser was dragged off the slide arc, hooked up to the failed machine, some tape wound onto the pulley... just how much was a big "guess", the negative carbon changed to a postive, the lamp lit up ready for change and over we went.
This was all done in the 20 minutes the other machine was running.
We ran all weekend like that with a quite pronounced pitch shift, up/down at each change but the show never stopped. [Wink]

During the week the failed rectifier was repaired but we forgot about the tape on the pulley until the first change... oops [Eek!]

Lindsay