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Shooting and syncing multiple tv screens


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#1 Mark Rimmer

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Posted 24 October 2005 - 04:54 PM

Hi
I need to shoot, on 35mm, a wall of 25 tv screens.
First question: Does using plasma or flat screen tvs eliminate the need for a sync between the camera shutter and the screen(s)?
2. How do I sync 25 screens to play 25 different video clips?
has anyone done anything like this before?
o yes, and how do you expose for tv screens?
thanks
Mark Rimmer Czech Republic
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#2 Clive Tobin

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Posted 26 October 2005 - 12:17 PM

Hi
I need to shoot, on 35mm, a wall of 25 tv screens.
First question: Does using plasma or flat screen tvs eliminate the need for a sync between the camera shutter and the screen(s)?
2. How do I sync 25 screens to play 25 different video clips?
has anyone done anything like this before?
o yes, and how do you expose for tv screens?
thanks
Mark Rimmer Czech Republic


LCD screens reduce the need for tricky techniques. I am not sure if they eliminate them entirely, perhaps someone else will have tried this?

If the video playback devices are professional grade, they will in most cases be able to lock to external sync. So you would loop a sync generator, or perhaps just composite video, through all of them and they should be able to genlock to the signal. If this doesn't work, you would have to connect each playback device to a TBC or Frame Synchronizer, in turn locked to the same reference. Once they are all running in sync, you could use our Milliframe Controller or other device with a Phase button, to put the bar where you want it in the monitor screens. By definition 25 screens will be small in the film frame, so it should be not noticeable that you are only getting half of the scanning lines when shooting at 25 FPS.

With 250 ASA daylight film, I would test at F/2 with bright consumer TV sets and F/1.4 with fine pitch pro monitors.
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#3 Mark Rimmer

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Posted 28 October 2005 - 09:55 PM

cheers clive
this might be a stupid question, but do lcd screens display 50 fields too, or is there such a thing as a progressive scan tv? i guess i could use video files shot at 25p.
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#4 Phil Rhodes

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Posted 28 October 2005 - 09:57 PM

Hi,

> LCD screens reduce the need for tricky techniques. I am not sure if they eliminate them entirely,
> perhaps someone else will have tried this?

Certainly on video they can shimmer, much less objectionably than a CRT monitor would, so I would assume similar things could arise on film albeit with a different characteristic. It's generally very minor.

Phil
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#5 Clive Tobin

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Posted 29 October 2005 - 03:13 PM

cheers clive
this might be a stupid question, but do lcd screens display 50 fields too, or is there such a thing as a progressive scan tv? i guess i could use video files shot at 25p.


I've never had occasion to be involved with LCD displays. An LCD backplane readout in a digital watch is excited perhaps 60 times per second, but the display does not noticeably flicker and in fact is quite sluggish to respond to changes, as the liquid has to physically reorient itself. If this carries over to the picture displays, it would make little difference how the material was shot.
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#6 Thomas Cousin

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Posted 31 October 2005 - 06:55 AM

hello,
the easiest solution is , in my opinion, to use lcd screen.
we regurarly shoot tv screens, computer screens, wall of screens for tv series, and now it's always LCD. we do not need to sync everything nor the cameras. we shoot 25fps 180° and just shoot the screen without worrying. it's the way to go for fast shootings.
bye

thomas
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