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Filming an LCD Projector


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#1 Craig Knowles

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Posted 30 November 2005 - 11:58 AM

I've got a shot coming up where the output of an LCD projecter will be visible in part of my frame.

My question is, filmed at 24 fps, will I get any sort of flicker in my final results? I am not familiar with how LCD projectors produce their output.

Thanks in advance.
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#2 Preston Herrick

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Posted 30 November 2005 - 02:04 PM

Good question. Since you can shoot an LCD display (unlike a CRT) without any flicker issues, and since LCD projectors are basically just an LCD panel with light pumped through, I'm going to deduce that there would be no issues there either. I'm sure someone else will chime in with a concrete answer.
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#3 Craig Knowles

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Posted 30 November 2005 - 03:01 PM

Good question. Since you can shoot an LCD display (unlike a CRT) without any flicker issues, and since LCD projectors are basically just an LCD panel with light pumped through, I'm going to deduce that there would be no issues there either. I'm sure someone else will chime in with a concrete answer.


That was my thought was well, but previous experiences have taught me that my thoughts are not always based in reality.

Edited by Craig Knowles, 30 November 2005 - 03:01 PM.

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#4 Phil Rhodes

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Posted 30 November 2005 - 04:00 PM

Hi,

Are you sure it's an LCD? DLP projectors can give trouble.

Phil
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#5 Craig Knowles

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Posted 30 November 2005 - 04:14 PM

Are you sure it's an LCD? DLP projectors can give trouble.


Yes, it'll be a regular old LCD projector hooked up to a computer.
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#6 oscar jimenez

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Posted 30 November 2005 - 07:48 PM

Well, check for Cycle change on the computer, so you can have set the monitor to your speed on cycles. Id rather shoot it at 23.97 Fps but if you have a CE Speed control base you can try with the phase button until scroll bar is out, there shouldnt be no flicker problems at 24 FPS, maybe just the scroll bar.
Cheers
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#7 Phil Rhodes

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Posted 30 November 2005 - 08:00 PM

Hi,

> Well, check for Cycle change on the computer, so you can have set the monitor to your speed on cycles.

That's a good idea, but many display drivers don't give you that kind of control.

> Id rather shoot it at 23.97 Fps

Why? That's got no clean mathematical relationship with any of the most common computer rates, and few computers let you set frame rates to a hundredth of a cycle per second. Even if this were the case, a lot of LCD display devices resample things internally to whatever rate they find most convenient, so it can all be a spectacular waste of time in any case.

> there shouldnt be no flicker problems at 24 FPS

What has 24fps got to do with anything? You could probably set the computer to output 72 or 96 (few will do 48, and absolutely none will do 24) and do OK on a CRT monitor, but 24 isn't a magic number in relation to computers.

> maybe just the scroll bar.

Even if an LCD doesn't shoot correctly, you won't get a rolling bar - it'll just pulsate slightly. Rolling bars are mainly a CRT thing.

Phil
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#8 Elhanan Matos

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Posted 01 December 2005 - 02:27 AM

The LCD part of the projector shouldn't give you any problems, but the bulb inside the projector might.
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