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Old December 2nd, 2012, 10:17 PM   #1
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Filming a Projector - Pulsing lines

Using Premiere CS6, is there any filter that will reduce/eliminate the pulsing scan lines that occur when filming a presenter in front of a powerpoint projected screen?
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Old December 2nd, 2012, 11:15 PM   #2
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Re: Filming a Projector - Pulsing lines

Not in post. The problem must be corrected before you shoot. Here in the US most projectors and PCs are set for a 60hertz refresh rate. Yours may be different. Before the shoot if you try different combinations of the refresh rate on the PC and your camera settings you can sometimes find a match that will give you a clean recording if you can find the sync spot.
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Old December 3rd, 2012, 02:42 AM   #3
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Re: Filming a Projector - Pulsing lines

You can't fix it in post. Sometimes there is no way of escaping it. I had a similar situation when filming a business presentation last week. The meeting room was well lit with fluorescent lights & as we are in the UK I shot at 1/50 which eliminates the flickering from 50Hz mains electricity. Unfortunately the projector was refreshing the screen at 60Hz & producing the interference. I had to make a choice between flickering light on the presenter & audience or shimmering on the projector screen & chose to have the Powerpoint shimmer. I have a copy of the slide deck from the presenter so proper images of the slides will be dropped onto the timeline in the appropriate place. It would be far more disturbing for the viewer to have the lighting wonky on the presenter than have pulsing scan lines on the screen beside her. To minimise the effect when it comes to the edit I'll use less wide shots than I would prefer & concentrate on the presenter & audience & have few shots with the screen.

If I had more time for setup & knew my way round that particular projector I might have been able to go into the menus & change it to 50Hz refresh if it had the option (many cheap projectors don't). I could have switched off all the lights & shot at 1/60 but then it would have been too gloomy for the presenter & audience.
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Old December 3rd, 2012, 08:24 AM   #4
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Re: Filming a Projector - Pulsing lines

Hi John

The Panasonic cameras have something called syncro-scan which eliminates the scan lines perfectly. Again you have to do it before you film not after. What I normally do is forget the screen and powerpoint and get a copy of the slideshow as PNG files and drop them into my NLE as overlays afterwards.

No really sure how to handle it in post though!!

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Old December 3rd, 2012, 11:11 AM   #5
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Re: Filming a Projector - Pulsing lines

Thanks guys.

Yes, I was informed at the beginning of the presentation that it was strictly powerpoint slides only and I planned to shoot talking head, and overlay the slides in post.

Turns out, the slides were full of technical data, the bloody laser pointer came out... embedded video and music, then to top it off, he dropped out of powerpoint and demonstrated a CAD-like program for 20mins to the audience.... had no choice but to pull wide.... that's when I discovered the flicker and no time to change settings. ARRRGGH.

I'm shooting with a Sony Z7 (HDV) which says there is a "FLCKR REDUCE" setting - will try this today onsite.
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