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Author
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Topic: 24 FPS Chatter on Sound Track?
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted July 01, 2007 07:29 PM
So, for a couple of years I've been operating my Elmo ST-800 on the dining room table and projecting on a screen in the living room. I decided to make the big leap: open up the porch doors, move the projector back about 8 feet and put some speakers up by the screen. I figure moving the machine further away from the audience and moving the source of the sound closer means the projector noise will be less intrusive.
It works...almost.
There is a chatter in the sound track that sounds almost exactly like the mechanical sound of the shutter/claw etc. I bet it has always been there, but when the machine is in the same room the mechanical sound drowns out the lower level sound through the speakers.
The interesting part of it is when the sound track is quiet, the chatter goes away, but when the level goes up, the chatter goes with it, as if it is modulating the audio.
Any ideas??
Thanks!
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All I ask is a wide screen and a projector to light her by...
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Gary Crawford
Jedi Master Film Handler
Posts: 979
From: Manassas, VA. USA
Registered: Jun 2003
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posted July 02, 2007 08:06 AM
Some of our more technical minded members can help more with this, but the super 8 clattering effect has plauged the format since it began. Old Standard 8mm had a long 56 frame separation between the intermittent movement of the film required at the gate...and the smooth running movement required at the playback head...plenty of time for a big capstan and roller combo , along with a flywheel to smooth out the flow. BUT on super 8 , the gate and sound head are only a second apart...(18 frames?)...anyway....a very short distance. rollers and capstans are smaller...and they have to be working almost perfectly....to smooth out that intermittent movement of the film. Also ...the sharp curve of the film coming out of the gate doesn't help. The problem is better or worse, depending on many things, including lubrication of the film. A clean well lubed film seems to do better. Clean good rubber on the capstan roller is a big help, too. The problem used to be worse in the early days of super 8 when soundtracks were recorded on projectors...all linked up together and recording at real time. The intermittent clatter was first sometimes recorded on the film to begin with....then when we got the film on our home projectors , the clattering of our machines was added to what was already recorded on the track.
Finally some say the problem seems less on color films of recent vintage...thinner stock.....some say older acetate films are less clattery.
Finally, if the projector is not setting that bottom loop exactly right, the film hits on the guides...and that just makes it jump even more...and the roller and capstan can't quite smooth it out. I'm sure there are technical folks who can add or subtract or correct me on these things, but this has been my experience and this is what some other experts have told me.
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted July 03, 2007 11:54 AM
I have to say Kev that I have never heard any flutter on the Eumig 900 series machines. The pinch roller and capstan on the Eumig's is very much larger than on the Elmo's, so this may be the reason why. Another factor may be that on the Eumig's the film path goes through a 90 degree angle loop before entering the (horizontal plane) sound head, thus effectively isolating the intermittent motion of the film coming out of the (vertical plane) gate. The corresponding angle on the Elmo's seems to be more like 45 degrees, which may not be enough to get total isolation of the film jerkiness. Also, on the GS1200's I have noticed that it is possible for the uneveness of the take up spool to sometimes transfer through the lower sprocket and cause up and down fluctuations in the black plastic tension arm, which presumably could influence the smoothness of the film velocity across the sound head. None of these problems are present on the Eumig 900's which have a much simpler film path, and possibly have the best sound reproduction of any super 8 machine. I'm not knocking Elmo's here, they are truly superb machines, but I think it's worth pointing out that in some areas 'The Wizards of Vienna' did a better job than the Japanese.
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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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