18 fps vs. sync sound vs. NLE

Erik Hammen · April 30, 2013

Hi folks -- I'm shooting a Super 16 film this summer with an Aaton XTR, which only runs sync speed at 24fps. However, how much drift is there really at 18 fps?

It seems to me that if every shot is slated properly, I could shoot at 18 fps and slow it down to 24 fps run speed on Final Cut Studio and be spot on to sync with the audio timecode most of the time, unless the camera really, really drifts.

The advantages would be

1 - I use 1/4 less film.

1 - I gain a stop

Disadvantages are obvious -- sync is off by enough that I go insane trying to resolve it.

What do you think?

thanks

Erik

Brian Drysdale · April 30, 2013

The motion won't look too good. It might be ok if things are fairly static. Having shot 8mm at that speed and then used 8mm at 24 fps on other films, I'd shoot at the faster speed unless you're going for a home movie look.

Pavan Deep · April 30, 2013

From personal experience I can say that the motion at 18fps is not always as fluid as that of 24fps, but then it's not bad either. I don't think that 16mm negative film gives that 'home movie' look either, I think 18fps can add a unique feel to 16mm. If there's a lot of movement 24fps is better it's also better for scanning etc. I don't think sync sound is an issue at any speed as long as you project at the same speed the sound would match, of course it depends on how accurate the speed of the camera is and whether it's speed is crystal controlled. If you film at 18fps then you must scan at 18fps because, if you scan your 18fps footage to 24fps it will be faster, you will need to slow it down in the NLE to match the audio.

Erik Hammen · May 2, 2013

The motion won't look too good. It might be ok if things are fairly static. Having shot 8mm at that speed and then used 8mm at 24 fps on other films, I'd shoot at the faster speed unless you're going for a home movie look.

Hi Brian, from what I gather, the motion is only an issue if the camera moves a lot.

What do you mean by "won't look too good"?

Erik Hammen · May 2, 2013

From personal experience I can say that the motion at 18fps is not always as fluid as that of 24fps, but then it's not bad either. I don't think that 16mm negative film gives that 'home movie' look either, I think 18fps can add a unique feel to 16mm. If there's a lot of movement 24fps is better it's also better for scanning etc. I don't think sync sound is an issue at any speed as long as you project at the same speed the sound would match, of course it depends on how accurate the speed of the camera is and whether it's speed is crystal controlled. If you film at 18fps then you must scan at 18fps because, if you scan your 18fps footage to 24fps it will be faster, you will need to slow it down in the NLE to match the audio.

I tend to agree, Pav -- but is there anything inherently wrong with slowing down the footage in NLE editing? I don't think it should degrade the image... The main thing I'm worried about is that there will be more sync drift once we're off 24fps than I can handle. The film doesn't have a lot of dialogue, but some elements of it are very naturalistic. I guess testing is the best route. Expensive, is the only problem, at my level.

Brian Drysdale · May 2, 2013

Any action will have less temporal information at 18fps than at 24 fps. It's the reason why I moved to shooting 8mm film at 24 fps because there was more noticeable blurring on any action at 18 fps.

Rudy Velez Jr · May 30, 2013

So if one where to shoot on super 8mm with a crystal sync camera, 24fps would be better than 18fps?

Brian Drysdale · May 30, 2013

I shot all my late 8mm at 24 fps because they looked better. 24 fps makes sense if you're shooting sync sound, since every means of distribution allows the use of that frame rate by some method or other..

Pavan Deep · June 1, 2013

For me the whole issue of frame rate is an interesting one, I know that 24 frames per second has been standard ever since the arrival of sound films in the 1920's. When using film most will film things at 24fps because that's how it's done professionally, but most of us don't ask the question why. Why is 24fps the standard? The standard speed could have been 20fps, 23 fps 26 fps etc. I wonder if 24 fps was chosen due to the infancy of the earlier sound recording devices? Maybe film needed to run fast enougth to produce decent quality of sound. I know that the faster the film runs it produces much smoother and more fluid and natural movement, some say that with a faster fps the grain is less visible, others say it adds to more realism. I have shot a lot of Super 8 at 24fps but I have also shot a lot at 18fps, the only difference I have noticed is that 24fps is better with handheld cameras whilst filming fast movement.

Slowing footage in NLE shouldn't be an issue as long as you've had a HD telecine, try and see. I have reently shot Super 16 at 18 fps and have had a 2k transfer and the slowed it down in NLE to 18fps and then synced my footage. The difference of my 18fps footage when compared to my 24fps footage isn't an issue for me as I hardley notice it and doubt that many would either.

P