Film-Tech Forum ARCHIVE: Kinotone & 25 Fps

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Posted by Demetris Thoupis (Member # 833) on 12-29-2002, 04:03 AM:

I've been thinking,
Most of you should know that electronic projectors made by Kinotone have a button which is called 25 fps. That of course makes the film go a bit faster. All digital equipment play fine of course and there is no visual difference to the audience. BUT if we come to the late long lasting films, like LOTR or Harry Potter then that option would surely shorter the film show time. By how much though? Does anyone know how many show time you save if you play the film in 25 fps for 10 minutes for example? Does anyone have any formula that can be applied?
Think good
Think Mechanical
Demetris Thoupis

Posted by Lionel Fouillen (Member # 1475) on 12-29-2002, 04:24 AM:

quote:
Does anyone know how many show time you save if you play the film in 25 fps for 10 minutes for example? Does anyone have any formula that can be applied?

Yeah, television.

Otherwise, I don't see any reason to project a film at a speed other than 24fps!

Posted by Stephen Furley (Member # 1277) on 12-29-2002, 04:28 AM:

You just need to divide the normal running time by 25, and multiply by 24. I make that 57 minutes and 36 seconds for each hour of film, a saving of 2 minutes and 24 seconds. I can think of a number of valid reasons for running film at 25 fps, but trying to save time is not one of them, and the time saved would be minimal.

The valid reasons I can think of all involve PAL or SECAM video:

The film was shot at 25 fps with the intention of transfer to PAL or SECAM, or was transferred from one of these, and this is therefore the correct speed.

To make a telecine transfer to one of these systems.

To make a side by side comparison of a film print and a video transfer made from it, or a video original and a film transfer made from it, for quality control purposes.

Posted by Stephen Furley (Member # 1277) on 12-29-2002, 04:44 AM:

quote:

Otherwise, I don't see any reason to project a film at a speed other than 24fps!

The film happens to be:

Original Todd-AO format, 30fps

Kinemacolor or Bicolor, 32fps

Showscan, 60fps

Silent film, could be just about anything from 14 to 24fps

Edison Kinetoscope film, I can't remember the speed, but it was much faster than normal.

One of the very few 48fps Imax films.

Shot at 29.97 or 30fps for NTSC video production without needing the 3:2 pulldown

Can anyone think of any others?

I have seen all of these projected except the Showscan and IMAX. They may not be very common, but they are shown.

At least getting a film projector to run at a non-standard speed is generally fairly easy.

Posted by Richard Fowler (Member # 893) on 12-29-2002, 07:47 AM:

Kinetoscope was 40 frames...the Lumieres brought this down to 16 frames per second average.

Posted by Lionel Fouillen (Member # 1475) on 12-29-2002, 09:21 AM:

Stephen,

I obviously agree with you regarding the non-standard or exceptional processes you mentioned. But I was just complaining about normal 24fps film projected at 25fps just to spare bulb lifetime or to allow for shorter performances !!!

Posted by Steve Guttag (Member # 268) on 12-29-2002, 09:39 AM:

Actually, the 25fps thing has been a standard since the "D" series projectors. Even inside the PK-60D there is a toggle switch (or there was the last time I looked) to set the projector to 24 or 25fps.

I normally reprogram it to 18fps for two reasons...one it allows the showing of "silent" films with a nominal slower speed if desired and two...if someone discovers the switch, it is obvious that the speed is in the right or wrong position.

Steve