Those rolling black bars...

[ExposedFilm]

Hello everyone!

Last week I shot a commercial in an old gym. Part of it was lit up with overhead neons, and (from what I understand), high shutter speeds and neons are a big no-nos. I ended up with vertically rolling black bars all over my footage. On some shots, it's barely noticeable, but two of them are problematic, especially now that they've been sent to grading and the blacks have been crushed. Aside from keeping contrast low and unblocking my blacks, is there anything we can do to fix those two shots? I've looked all over on the Internet and so far, I'm guessing the damage is irreversible. I'd be happy if someone could prove me wrong!

Also, as a reference, is there anything I could do to avoid those black bars in the future?

Cheers!
Charles

 

[Renee]

I think this may be your problem but I am not sure.

As I understood it - the trick is the shutter speed needing to be divisible by the frequency of the light - for the US its 60hz.(30 / 60 / 120 ) For most of Europe it's 50hz.

Could you drop your frames down to something like 24p and see if it lessens some of the flicker? It may not help, just a thought.

 

[Alex H.]

Not sure dropping the frame rate will help. Those rolling bars are present on every frame of the footage, and once it has been recorded it is pretty much there.

But yes, the frame rate needs to match the electrical system. Speaking in terms of NTSC: Lots of folks try to stick with the 180º rule, or 1/50 for 24fps. This will only work reliably under natural light (sunlight). Some artificial light is worse than others (incandescent isn't a huge deal, but HMI and florescent are terrible as is the gas lighting found in most gymnasiums), so it's best to stick with 1/60 under any light besides the sun.

 

[mcbob]

Depending upon how much movement is in the shot, it may be possible to composite-overlay or soft/hard light nearly identical footage at a time offset where the black bars don't overlap... it won't be perfect, but may diminish the bars' appearance.

 

[ExposedFilm]

Thanks for the replies guys. I remember that on my DVX, there was a setting to "conform" to film, say, a television set and remove the flickering. I completely forgot about the neon flickering and the shutter speeds. I saw some lines on the monitor but I thought it was the monitor acting up. Most of the "worst" stuff is shot handheld so dodging probably wouldn't work. I'll make a note to test different shutter speeds under neon lights to see what helps most. My talkheads shots at 1/50 are fine, but the action shots (between 1/500 and 1/1000, if I remembered right) have the bars. It's now the only thing I see when I look at the footage but my roommates never noticed, so I guess it isn't as bad as I make it to be!