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How do I film a computer/video screen without it flickering?

Internet Filmmakers' FAQ

Filming of a computer screen requires the camera speed to be synchronised with the scanning rate of the monitor in question. There are several ways you can do this.

1) You need a CEI film/video synchroniser which connects to the monitor/computer and replaces the camera's internal sync with that of the monitor. You then have to start your camera rolling as the monitor starts any given scan otherwise you will get a black interference line somewhere in the picture. This can be a bit fiddly to achieve, but you just need to keep trying. All you do is stop and start your camera whilst looking through the viewfinder until you get a shot where the line is not visible (and keep your camera running!). Note that this solution is only suitable when you're shooting with film.

2) There is a cheaper and less convenient way to do it. All you really need is a speed control that that goes down to the one-thousandth of a frame per second and has a phase button. This generally rents for less than half the rate of the CEI f/v sync. Or, if you have newer camera like the Arri SR3, these features are actually built into the camera. Then you just run the camera, adjusting the frame rate until the dark bar completely stops moving. Make sure you take the magazine off first! Push the phase button and watch the bar scroll out of the screen. You are done! You *should* be able to start and stop the camera at will, now. At worst, you will just have to phase the bar out of picture area before you call action.

If you have a little more money and don't want to waste time, you can rent a little item called, I believe, a Cinches. This little device measures frequencies. It works on lights, monitors, etc. Unfortunately it only gives readouts to the hundredth of a frame per second, and when checking monitors it actually gives field rate, not frame rate. Still, this will make things go faster and although you still need the speed control the two are often still cheaper to rent than the CEI f/v sync box.

If you have the money, though, the sync box is probably the way to go. It is the most accurate, it is constantly connected to and controlling the camera so that if for some reason the frame rate changes the camera speed will change as well (this is especially common in computer monitors as different programs will often cause the monitor to run at slightly different speeds. Additionally, and here is where the second error comes in, you do not need to keep the camera running. Check your sync and phase out the bar before you start shooting (again, take the mag off). Once you're set you should be able to start and stop the camera at will, and not even have to phase the bar out each time you restart. Detailed information regarding filming computer screens can be found in the American Cinematographer Manual, published by the ASC.

For video cameras, things are a bit trickier. You really need to have a camera where you can adjust the shutter speed (a feature normally found on higher-end cameras). For filming a screen/monitor, you need to get your shutter speed in time with the refresh rate of that device (1/50th second for PAL TVs, 1/60th second for NTSC etc). Unfortunately computer monitors all have different refresh rates (as a result of both manufacturer decisions and end-user settings). If you really need to film a computer monitor, consider using a laptop or flat panel, as these types of monitors don't refresh in the same way as CRT monitors.

Answer by Benjamin Craig  |  Last updated 14-Jan-2005

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