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Topic: Conversion to digital - lots of flickering
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John Whittle
Jedi Master Film Handler
Posts: 791
From: Northridge, CA USA
Registered: Jun 2003
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posted December 20, 2005 10:04 AM
quote: I have a question : is it the nature of the beast that there is flickering when converter 8mm to digital using one of the those cheap telecine converters (projector one end, DV cam in the other)? I wasn;t sure if it was just me or that is what all transfers look like...maybe it is my eumig624d projector?
What you have to do will depend on the television standard where you live. If you're in the US, then the NTSC standard produces 30 pictures per second (nominally, in color it's actually 29.94 due to timing differences with the color subcarrier).
In order to transfer film to video, you must match up the frame rate of the film to the field rate of the video with a whole number.
Thus 30 frames of video is made up of 2 fields each and yeild a number of 60.
If you take silent film and a projector with a three blade shutter and run it at 20 frames per second you'll get 60 interruptions and match the video field rate. If you want to run a slower speed (say 15 frames per second, 16 won't work), you'll need a four blade shutter and then you get 60.
If you have sound film, then it's 24 frames per second and a five blade (interruption shutter) and you'll get 120 which is equal to 2 x 60.
To get rid of the ground glass effect, you'll need to set up an aerial image table which consists of a diffusion glass behind the projector aperature and a field lens. Then the image is created in thin air (just the way Donald Duck danced with Carmine Miranda) like a film chain. This produces the best contrast and sharpness and can be a bit diffcult to set up since it is really an optical bench. To get your image correct left to right, you'll need a front surface mirror in the set-up.
A synch motor on the projector will help matters, but if you have a good solid state speed controller built in your projector (and not a simple induction motor) you probably can get by with that. An iris on the projector lens will help in setting the light output of the projector. Putting a resistance on the lamp will change it's color as you lower the lamp output.
John
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