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Experimental S35mm Telecine Underway


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#1 Adam Van Voorhis

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Posted 22 February 2011 - 12:01 AM

Last year I began the process of constructing an experimental S35mm Telecine out of a pair of gutted tabletop Analysis style silent 35mm projectors. Results with a Red One & 100mm Macro Lens pointed at the gate were very promising, considering the little effort I had put into the project.

I am now replacing the lamphouse with a more appropriate color temperature controllable led light source than before.

While I have a contact closure trigger tapped off of one of the existing motors and am able to drive single frame capture on the red via a simple relay board the image steadiness is a huge issue at any speed.

The projector has a movement controlled by two separate motors. One drives an eight pin rake that constantly speeds back and forth across the film, while a second moves the whole rake/claw/pins just in time to engage the film and hold it in place for projection at your desired frame rate. Its pretty scary to watch and loud, even at 1fps.

So my plan has been to replace this constant motor with a large software controlled 12V stepper motor and relays with USB boards from pc-control.co.uk. I have most of this gear on hand now. Of course, I basically am replacing all the motor drive in the projector's movement, while slowing down the system to a much much much slower pace.

If anyone has any ideas, other than to tell me this is a crazy waste of my time, i'd love to hear them!
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#2 Chris Burke

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Posted 22 February 2011 - 09:48 AM

I am trying this out this week, or at least starting to modify the projector, with a sixteen millimeter set up. I will let you know how it turns out. Why are you using the red camera? I would think that there are better cheaper options.
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#3 K Borowski

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Posted 22 February 2011 - 12:33 PM

Good idea switching to LED lightsource, but I think you should take it one step further and have an actual additive lamphouse on the front where you can actually control individual red, green, and blue color components. Adjustable color temperature, if I recall correctly, lets you do *some* of that, but not all of the flexibility of a true additive, light mixing lamphouse.

You can use subtractive filters, but then you have to contend with filter factors as when you subtract light you are losing intensity through the filters.



Even with additive there is loss, color contamination, but I think the results are much better than trying to correct in the digital realm, where heavy coor adjustments aren't as lossless.

If I were doing this (with so much gear being thrown out I personally don't see the need), I would use color filters, rather than a camera with RGB photosites to sample each color. Since you are scanning a single piece of film there's no need for real-time imaging, although, even here with a fast-enough setup you can get pretty close spinning filters.
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