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Getting a 35mm projector this week made for telecine


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#1 Zachary Vex

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Posted 19 December 2006 - 09:46 PM

I'm getting a projector that was specially designed for TV stations to broadcast movies using real-time telecine. It has the ability to instant-start, instant-stop, and advance single frames... there are special servo circuits and sensors that keep the frame perfectly registered using measurements taken from the edges of two perf holes. There's no pull-down... there's a sprocketed wheel driven by a powerful servomotor that advances the film so fast it's completely invisible to the eye.

My question is this: After I've diffused the light source and obtained a very long lens to flatten out the image for my HD camera to capture directly off the projector, what can I do to synchronize the frames so there are no partial frames in the video? The projector provides 3:2 pulldown for telecine and syncs to the 60Hz mains unless provided with a video sync pulse, but I'm using a consumer (Sony) HD camcorder to capture and I don't believe there's any way to sync. I'm afraid I'm going to see overlapping frames as a result of the lack of sync... what to do?
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#2 Hal Smith

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Posted 19 December 2006 - 10:10 PM

there are no partial frames in the video? The projector provides 3:2 pulldown for telecine and syncs to the 60Hz mains unless provided with a video sync pulse, but I'm using a consumer (Sony) HD camcorder to capture and I don't believe there's any way to sync. I'm afraid I'm going to see overlapping frames as a result of the lack of sync... what to do?

If you're real lucky there's a composite video input on it, HD downcoverted to an SD signal should lock it up just fine (your camera has an SD output?). Since 3/2 pulldown is built-in, it'll project at 60i (actually 59.97i).

If it doesn't have any inputs other than standard house sync inputs then a standard broadcast sync generator with a genlock input should do the trick. Feed downconverted SD into the genlock input and sync outputs to the projector. Sync generators can be rented if you want to fiddle before you buy.
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#3 Zachary Vex

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Posted 20 December 2006 - 02:05 PM

If you're real lucky there's a composite video input on it, HD downcoverted to an SD signal should lock it up just fine (your camera has an SD output?).


A composite input on the projector? No, unfortunately only a video sync (bnc connector). My camera does have an SD output (simple yellow RCA with stereo audio) along with composite HD.


Since 3/2 pulldown is built-in, it'll project at 60i (actually 59.97i).


Does it do that by changing the flashing rate of the shutter so that 2 frames of film image 1 are illuminated, then 3 frames of film image 2, and that's repeated 12 times in one second for a total of 60 frames?

If it doesn't have any inputs other than standard house sync inputs then a standard broadcast sync generator with a genlock input should do the trick. Feed downconverted SD into the genlock input and sync outputs to the projector. Sync generators can be rented if you want to fiddle before you buy.


Sounds good. I'll have to investigate inexpensive genlock-input broadcast sync generators.
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