Question: Super 8mm Crystal Sync

[Derek Van Gorder]

Back with another Super 8 question. So I know that in order to shoot sync sound with Super 8, you'll need a camera with crystal sync in order to guarantee a constant 24 fps. But while looking into that, I've been told that the developed film then also needs to be transferred specially in order to maintain that frame rate into a digital post workflow, and this process is somewhat pricey.

I am wondering: if I shoot crystal sync but transfer normally, is the sync drift less than if I shot on a camera without sync? Would it be worth renting a crystal sync camera if I then transfer normally, or is that pointless? And does anyone have any experience with how bad the drift is and how long it takes before it is noticeable? If I shot dialogue in 30 second takes or less, will it be possible to match up the audio in post?

Thanks!

 

[Dan Hudgins]

Projector speed

Projector speed

And does anyone have any experience with how bad the drift is and how long it takes before it is noticeable?

To transfer the super8 film to video?

You have two problems the NTSC video runs at 59.94005994 fields per second and if the projector has a 60Hz sync motor the projector will probably run at 24fps.

If the video ran at 60fileds per second then you have a 2.5 ratio of the frame rates, but because of NTSC you get an odd ratio, unless the sync motor is driven from the video Hz.

If you are going to PAL you have 24+/- to 50Hz issues.

Projectors that do not have a sync motor may vary in speed up and down do to rubber drive rollers and other mechanical issues, so it will not hold 23.5fps or 24.5fps or whatever speed over 30 seconds, making the sound both ahead and behind at times.

If you slate the shot both at the head and tail, you can count the video frames after the transfer and resample the audio to fit, or resample the video frame rate to fit the length of the audio.

VirtualDub can resample the video rate, and Magix can resample the audio rate, so you can get a rough match.

It would be much better to use a Digital SLR to make a film scanner to shoot off the 24fps Super8 and get true 24fps frame rate image frames, you can make a scanner out of an old Super8 projector, a gear or stepper motor, and my scanner program DANCINES.EXE (tm).

You can see some sample scans from Super16 at these links, sign in to see the images and thumbnails,

http://reduser.net/forum/showthread.php?t=28486&page=5

http://reduser.net/forum/showthread.php?p=402805#post402805

My scanner software can read a script file, so you can have it skip over the parts of the roll you do not want scanned. You can mount a "D" mount 36mm lens backwards to use as a scanner lens. Cut a hole in a body cap for the DSLR and glue some PVC pipe on it, you can then wrap the lens so that is fits snug and slide it in and out to get the right focus and magnification.

My edit system lets you edit at true 24fps also.

Remember when you record the audio you need a crystal sync recorder, or need to use pilot tone. I have a Bolex spring wind that I put a "60Hz" pilot tone generator on to record sound on Cassette some time ago, it works even though the camera varies between 23 and 25 fps during the take since you resolve the audio to mag film by driving the mag film recorder motor with the pilottone from the tape playback. You can put a pilot tone generator into almost any movie camera Super8 or other, you need to find a shaft inside that is 8 frame or so and you out a Steel or Iron gear on it and a tape head and a magnet, so you get a mic level 60Hz or 50Hz output. After you resolve to mag film, you play back at line sync into a computer sound board to get a sync WAV file, etc. When you use polot tone you record on a stereo tape recorder, audio on one channel and pilot tone on the other channel. If the camera is crystal but the tape recorder is wild, you can use a 60Hz line transformer and a -20db line pad to get line sync pilot tone, but only if you are near a wall outlet.

Various WAV recorders sold that record to SD or CF are crystal, also VHS HI-FI video tape is crystal controlled, Mini-DISK also works.