18 fps with external sound

Zensteve · Mar 24, 2005

From what I understand, film used to run at 18fps 'til the advent of the first "talkies" and the switch to 24fps was made. This was apparently because the room needed for the sound-stripe needed more length than frames... or something like that. :weird:

Nowadays Super-8 can only be silent and sound is recorded independently, not needing that extra frame-rate...

Specifically, my question is this:

If I film something at 18fps with the intention of having it played back at 18fps (as the normal speed), will the sound recorded on the other device still drift away fast... or will it match?

(This is not related to the crystal-sync issue, to clarify)

Will Vincent · Mar 24, 2005

If the film is recorded at a constant rate ... no matter what the rate is, 8000fps, 18fps, 24, etc.. and played back at that consistant rate.. as long as the audio was recorded at a consistent rate, and is synched, it should not drift.

(to clarify, yes.. it is technically still a crystal sync issue, just at a different speed...

)

Will Vincent · Mar 27, 2005

It depends on the telecine... the guy at the cine place here told me there is absolutely no difference in final product.. so since Zen's planning to telecine and finish on digital anyway, 18fps is the way to go.. get a little more time for each roll of film.

Zensteve · Mar 27, 2005

It's a bit of a complicated issue... and I thank you for the replies.

I get confused rather easily, when fps's are concerned. An 18 fps film with sound (non-synced) recorded on a DV camera recording to audio at 30 fps? Boggles my mind :cool:

The decision to shoot at 18 fps is a bit of a tradeoff, yes. My camera has 3 speeds... 12, 18 & 24. If I choose 18 for the "main" speed, I have the options of fast & slow motions. 18 is the middle speed that I can get. It may be a bit more flickery yes, but I can get the effects I have in mind.

Film is so hard! But fun :yes:

Zensteve · Mar 30, 2005

Sooo... you mean an 18 fps 'cined at 18 fps can be mixed with 24 fps footage ('cined at 24 fps) and they will look like they are moving at the same speed? (flickery bits on the 18 fps, aside)

Will Vincent · Mar 30, 2005

As long as the different speeds are on seperate reels, and you tell the telecine folks what speed it's filmed at then, yea.. it should all run the same speed. More or less.

Zensteve · Apr 1, 2005

Okay, one more Q while I think I have this straight.

I could also film something at 24 fps, and tell the lab to 'cine it at 18 fps... and I could in theory generate a slo-mo effect like that? :eek:

Shaw · Apr 1, 2005

Will Vincent · Apr 1, 2005

that's how the pros do it.. well most of 'em.. some probably do it digitally these days

Zensteve · Apr 1, 2005

You guys are awesome!

jaxshooter · Sep 30, 2005

Even if you don't have crystal,if your camera has a PC jack for a flash you can use this for syncing at either 18fps or 24fps.Basically your camera puts out a pulse every frame that can be amplified and recorded onto an unused audio channel.What you end up with is a record of any slight speed variations that can be used as a refference when you resolve your audio in post.
Personally I would stay away from anything but standard 24fps.