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Chris Rhode

chrisrhode@hotmail.com

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As Pat Moore noted, the projector positions the film laterally using the "reference edge" of the print (analog soundtrack side). The lateral edge guiding in the projector is provided by the fixed guide roller and/or the outboard "studio guide" rail (they can interact, depending upon how they are aligned). The inboard spring-loaded guide roller "pushes" the film against the fixed roller/guides to position the film laterally. The inboard studio guide rail (if used) should NOT be set up to "pinch" the film into position.

You are putting cue tape on the outboard (reference) edge of the print. Since this is the guided edge of the print, the film jumps laterally as the tape goes through the projector gate. The projector is doing its job correctly --- the cue tape overhanging the edge is the likely problem. Using a fixed inboard "studio guide" to pinch the film into position would not solve the jump problem, and would likely catch on the added width of the tape or any splices.

If you don't "wrap" the tape around the edge of the film, and trim any overhang carefully, you should find much less sidewise jump.

BTW, the intermittent sprocket should ideally NOT provide any lateral guiding via the perforations. The film should be aligned so the sprocket teeth are centered on the perforations. This applies to both the old style "narrow tooth" CS sprockets, and the "Very Kind to Film" VKF sprockets that are most commonly used today.

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But because the teeth on one side are effectively "full fitting" widthwise, care is needed to be sure the gate alignment is "perfect", or else the sprocket teeth "fight" the edge guides for control of the film's lateral position.

I'm sorry to hear that LaVezzi may have discontinued them. They were great if you knew how to set up the alignment perfectly.

BTW, I hope no one is still using narrow CS-tooth sprockets anymore, unless they need to show an old 35mm mag-striped print. Those sharp 0.040 inch wide teeth were tough on perforations.

Rather than continually extending this topic which could get to be QUITE long over time, maybe we should post individual topics with the manufacturer's name as the first item in the topic title. This would make it much easier to spot for whoever needs to answer the question or concern or problem.

Some examples:
SMART: automation not shutting down at end of show

SMART: Need hookup info for DA20 to MOD V

DTS: Out of sync sound

STRONG: picture jumping at cue tape

Anyway, you get the idea.

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Oscar Neundorfer
Chief Engineer
SMART Devices, Inc.

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What you just said makes perfect sense. I don't understand why I didn't figure that out. I will try and cut the cue tape in half because the tape that we use is made to wrap around the side where you place the tape on. I don't know why they decided to do this if it causes this problem. What would be the best way to cut the tape in half evenly?? The only way I can think of is to use a razor blade and cut VERY CAREFULLY down the middle of the tape.

Thank you for making this clear. But I still have one last question, if you don't put a guide on the other side of the gate, then why pre-drill the holes. Is it for the consumer in case they decide to move the guide over to the opposite side??

Thanks for helping me out everybody!! I've learned more in the past 2 weeks from visiting this website daily than I have learned from working in projection for the past 8 months!!!

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Chris Rhode

chrisrhode@hotmail.com

Bill, my theater is not going to spend the money to buy 24 new cue detectors just to eliminate that little jump in the picture. If I had it my way, I would get rid of 80% of the crap that we use, but since my theater is already 125k or so in the hole, that is out of the question.

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Chris Rhode

chrisrhode@hotmail.com