Film-Tech Forum ARCHIVE: Brings a projector down to 18FPS?

This is topic Brings a projector down to 18FPS? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=010481

Posted by Paul Gordon (Member # 3320) on 05-30-2010, 09:23 AM:

Whats the best way get a projector running at around 18fps for silent films? We have a 4-star sound head running a Century C and want it to run 18fps for some silent films. Is there an easy way to do this? What will it take? Thanks

Posted by Jack Theakston (Member # 4484) on 05-30-2010, 10:28 AM:

Variable speed motors that can be controlled remotely (I'm sure others here can elaborate as to what is best currently).

18-20 fps is the threshold of how low you can go without getting some serious flicker without replacing the shutter with a 3-blader, so consider that. You'll also need new aperture plates and be able to offset the projector to silent-center if you're getting an archive print that hasn't been optically reduced.

Don't make the mistake of assuming all, if even most, silent films are meant to be projected at 18 fps. After about 1923-24, speeds in the area of 22-25 fps were the norm.

Posted by Martin McCaffery (Member # 37) on 05-30-2010, 11:07 AM:

As much as I hate to say it, if this is a one off thing a good transfer DVD may be your best bet.

The transfer should be at the correct speed, so you don't have to worry about it. It was probably made from the best available source. And as it is in B&W, will look decent on the screen. Your quality tradeoff is going to be the condition of the print vs the DVD. Obviously, you don't have to worry about sound.

On the other hand, if you're going for a semi-permanent silent film venue, good for you and go for it, keeping in mind what Jack said. I believe there are threads about the specifics for the mechanics, and if not, someone will be here soon.

Posted by Monte L Fullmer (Member # 2797) on 05-30-2010, 01:10 PM:

True, before the standard 24FPS film speed was established, there was no industry standard in silent film speeds since a lot of those early cameras were hand cranked and not motor operated.

You could bolt up a motor underneath the 4 Star motor mount.

On the top motor, remove the front knob and mount a larger diameter pulley on the end of the motor.

Then, the motor underneath will have a small diameter pulley and that motor will run the upper pulley, via a "v" belt, attached to the main drive motor in a reduced RPM.

You would have to find the ratio for the correct pulley diameter (buy an adjustable pulley that you can change inside widths) since your reducing shaft speed to run 24FPS, or 1725rpm down to 18FPS.

(Plus, you know that you're gonna get some flicker on the screen since you're also reducing shutter speed from 48 flashes down to 36 flashes per second...)

Power to that lower motor will have to be separate to a simple plug in the wall, or add a switch inbetween the wall cord and motor.

..for I've got to do the same thing come fall - to slow down an XL with a 4star underneath of it do do some silent films.

ALSO, doing silent in a sound projector, you know that you're gonna have to cut new aperture plates to capture the entire frame since there is no soundtrack on a full-frame, silent image.

Plus, do an adjustment to the lens so it can be in optic center of the frame since it's off to one side also due to the soundtrack frame of sound film.

Good luck-Monte

Posted by Paul Gordon (Member # 3320) on 05-30-2010, 01:12 PM:

We play a lot of silent films...and the film is a new 35mm print that is tinted. The film came out in 1919 so it was run then at 18fps.

Posted by Gordon McLeod (Member # 33) on 05-31-2010, 01:00 AM:

you need to get a 3 phase 1800 rpm motor and then a Variable Frequency Drive (i recomond the Baldor ones)
At 18fps a three bladed shutter is needed also 18 was not common early films were often 16fps but there never was a "standard cranking" rate and many films came with cues sheets to varry the projector cranking speed for different scenes

Posted by Jack Theakston (Member # 4484) on 05-31-2010, 01:51 AM:

Silent film speeds, like aspect ratios, are apparently another touchy subject with some film scholars. But it is established that during the silent era, most documentation points to the practice of editing and running the films slightly faster than they were shot (hence the undercranking of films during the transitional era when the filmmakers knew that the picture would have a synchronized score at 24fps).

Speaking of which— what is the film you're running?

Posted by Paul Gordon (Member # 3320) on 05-31-2010, 06:26 PM:

Back to God's Country. The oldest surviving Canadian feature film.

Posted by Josh Jones (Member # 447) on 06-01-2010, 12:51 AM:

In the past, I seem to recall the inching knob of our XL being replaced with a pulley, and a piece of wood bolted to the bottom of the motor mount, and a drill press motor mounted on the other side. Our setup ran at about 19 FPS, mainly because at that speed, the intermittant got at least some oil [Smile]