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How to control the frame movement , while shooting a "tv screen" or "computer monitor"?


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#1 deepak srinivasan

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Posted 03 February 2011 - 08:49 PM

i am shooting a short film now , there is a scene in it where we show a person running in the corridor and suddenly pan and show a t.v. screen (Surveillance camera footage). am going to shoot this scene next week. i know if you shoot a screen u can see the frame moving upwards. so before going for shoot i want to clearly know how to control it.
kindly answer to this question :)
THANKS IN ADVANCE
CHEERS!!!
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#2 Brian Drysdale

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Posted 04 February 2011 - 04:50 AM

It really depends on how stable your CCTV video input is. Assuming it's a CRT television and the video is stable, a crystal speed camera shooting at 25fps (since you're in a PAL country) and using a phase control unit to remove the bar. These may be built into the camera or they are available as an accessory.

As mentioned in answering your other post, you need to use your real name.
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#3 Keith Walters

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Posted 04 February 2011 - 11:13 PM

i am shooting a short film now , there is a scene in it where we show a person running in the corridor and suddenly pan and show a t.v. screen (Surveillance camera footage). am going to shoot this scene next week. i know if you shoot a screen u can see the frame moving upwards. so before going for shoot i want to clearly know how to control it.
kindly answer to this question :)
THANKS IN ADVANCE
CHEERS!!!

If you're using a video camera to shoot your project, even if you do manage to get the frame syncs right, you still can't move the camera while shooting a CRT monitor, because you'll get all sorts of white line artifacts on the image of the screen.

By far the simplest solution is to use an LCD monitor to display your "surveillance" footage. That way you shouldn't have any sync problems of any sort. As far as the camera is concerned, an LCD image behaves like it's printed on paper.

What you could possibly do is mount a standard LCD computer monitor on the wall, and play your footage through Quicktime or something similar on a standard computer.
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#4 deepak srinivasan

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Posted 05 February 2011 - 03:24 AM

If u shooting in a film camera (like 435) what ull do to get rid of the lines ??? ull use frame rates or shutter angle to compensate that
and , i wanna know why those lines even come ??? in naked eye those lines are not visible
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#5 Brian Drysdale

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Posted 05 February 2011 - 05:20 AM

You use a combination of frame rates and shutter angles and then use the phasing unit to remove the bar from view. As mentioned the LCD screen doesn't have the problem.

Your eyes don't use frames to record your view of the world. Film and TV frame rates are selected so that persistence of vision allows you to view without flickering, usually by repeating each frame a couple of times in the viewing system or at a high frame rate eg 60p.

The camera is recording regular intervals of time from a CRT which displays regular intervals of time, if they don't match up i.e. out of sync you see the bar between the frames. It's a bit like a strobe light being used to set the timing on an engine
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