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Shooting off a TV screen


Panayiotis Salapatas

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Hi-

 

If the TV is very prominent, like a close-up, to be extra safe you need to set your shutter at 144 and use the synco box to phase the roll bar. You can also get the little doo-hickie that sits behind the TV and reads the TV's CRT, and automatically phases the shutter to match it.

 

Or just set your shutter at 144 and shoot away, that's worked fine for me too.

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If the TV is smallish in the BG and not to important, go with the plain old 144 degree shutter. If it's a major story point, there are 24 frame video services that will put your material on their CRT's at 24 fps with shutter sync. That lets you shoot the film completely normal, with a 180 degree shutter.

 

With freewheeling 144, you still get a roll bar, but its height is zero lines. If you can see the set well enough, you can see the offset on horizontally moving objects. (Of course, if there isn't much movement, you can get away with this.)

 

Another possibility is to use an LCD display instead of a CRT. Should be tested, but they're usually much better behaved than old time tube TV's.

 

 

 

 

-- J.S.

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Hi,

 

Any suggestions on how to shoot off a TV screen (35mm at 24fps) in the US and not get a flicker from the 60Hz cycle?

 

Thank you

ps. the 35mm camera is a Moviecam compact

As John said, all modern LCD screens are completely strobe-free, and very cheap now.

If the TV has to be an old-fashioned type to suit the script, the easiest solution is to find an old junked CRT TV, get a repair shop to remove the picture tube (as this can be dangerous if you don't know what you are doing) and fit an LCD screen in its place.

 

In the past, a common trick was to use 25 fps PAL video and a PAL (or multistandard) TV and run the camera at 25 fps, synced to the video frame rate, either automatically or manually (with the "phasing" button). When the film is then run at 24fps, the action slows down by 4%, but nobody will notice that.

 

If there are actors in the scene this becomes more of a problem if they have to speak, because slowing down the sound recording to match the picture would produce a sudden 4% pitch change, which is quite noticeable.

 

If it's only a short project such as a commercial, you can simply shoot the whole thing at 25fps, because in most cases people won't notice an overall 4% pitch change, only it it changes from scene to scene.

 

Otherwise, another common trick is to always have the speaking actor's back to the camera and have them dub the sound in later.

 

Nowadays, most larger post production houses have pitch changing equipment that solves this problem. Even some really cheap DVD players now have this feature!

Edited by Keith Walters
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I guess you could, but again, it's very simple and takes about 10 seconds to set the shutter at 144 degrees.

 

If you want to get really fancy, hook up the synco box and phase the shutter, which takes an additional 30 seconds, problem solved.

 

Or do as Keith suggests and plop an LCD screen into an older TV case.

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Seems like a green screen thing could be applicable here. Just paint the CRT screen on a junk TV and add the animated image in post? Anyone know the trick to that?

Actually, just feed 100% full frame green only to the TV set. You want a bright bright green, and since there's no content, the 144 degree shutter will work fine. Video playback is easier to do and usually looks a little better, but sometimes you don't have the plate in time, and have to burn something in. The other potential issue is if the actors have to react to something that's in the TV plate. It helps to have the real thing.

 

 

 

-- J.S.

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Seems like a green screen thing could be applicable here. Just paint the CRT screen on a junk TV and add the animated image in post? Anyone know the trick to that?

That approach works reasonably well for a locked-off shot where the camera is directly in front of theTV screen. If the camera is off to the side however, the perspective will be wrong and you will have to correct for that in the keyed image. If you have to do a tracking shot or a zoom, having an actual image on the TV screen is really the only way to go. And if you are using a photochemical post chain (ie no DI), in all cases it this will make things vastly easier.

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  • 14 years later...

Bumping this topic.  ?

I have a Moviecam SL with a Synco box and I want to film some detailed CRT shots ala reverse telecine -- both where the CRT tube is shown, but also macro shots where I can visibly see the scanlines and aberrations on screen. The footage will be played back at 29.97i and captured at 24fps.

I have done it thousands of times in post, and also filmed off CRTs with digital cameras, but I want to use the Synco box with some home videos off a VHS deck > old Tube TV. The sync is a 5V TTL, as per the Moviecam Compact Manual:
"[C] Fig. 155 – THE SYNCOBOX

Apart from an exact and repeatable synchronization of the MOVIECAM COMPACT with video and computer images, the camera may also be synchronized with generators, other film cameras, front and rear projectors etc. The SYNCOBOX can process any 5 V SYNC signal (TTL) or video norm signal (1 Vpp).

The frame speed input at the control board and the crystal control of the MOVIECAM COMPACT are inactivated by mounting the SYNCOBOX."

This anomaly of early HDTV is a combined Digital AND Analog VHS deck that has both component and composite output, which I would use as my playback deck.
http://support.jvc.com/consumer/product.jsp?modelId=MODL027070

Theoretically speaking, would this work? Asking for a friend, before we waste a bunch of time and film.


Todd

 

page185image50766368.png

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55 minutes ago, sines said:

Theoretically speaking, would this work? Asking for a friend, before we waste a bunch of time and film.

If you give the synchro box a composite signal, theoretically it should work. But I believe you have to set the shutter properly as well, it's not a one stop plug in the box thing. Do you have the American Cinematographer manual? They discuss this in great detail. 

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Yep, I got 2 copies of the manual, plus Samuelson’s bible. I am guessing that the video input on the Moviecam is composite, not component. It’s separated on a component signal and carried I believe on the Y (R) channel. 

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With a 59.94 hz CRT video image shot at 24 fps, there are actually two (or three) roll bars. Setting the shutter to 144 degrees makes them thin lines rather than fat bars. Using a phase control and running the camera at 23.976 fps allows you to stop the rolling and move those lines either to see only one in the center or two lines at the top and bottom third of the frame.

The only way to not have any roll bar / lines is either to shoot at 29.97 fps or use a special 23.976 fps monitor and deck with footage converted from 59.94i. Or use a flatscreen LCD monitor.

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8 hours ago, sines said:

Yep, I got 2 copies of the manual, plus Samuelson’s bible. I am guessing that the video input on the Moviecam is composite, not component. It’s separated on a component signal and carried I believe on the Y (R) channel. 

Yep it's 525i composite, not component. Y is the carrier. Pb, Pr are the blue and red. 

Edited by Tyler Purcell
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