thotter11
Level 1 (0 points)

Q: How to remove Horizontal light bands

I recently shot a music video and am finding strong horizontal light bands in the footage. They were not very present on my monitor while filming and I was in, what I thought, was an apporpriate shutter speed.

 

I am having difficulty trying to edit them without the 3 way color correction.

 

Any suggestions or tutorials you could throw my way?

MacBook Pro with Retina display, OS X Yosemite (10.10.4)

Posted on Sep 24, 2015 4:11 PM

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thotter11

Q: How to remove Horizontal light bands

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  • by Russ H,

    Russ H Russ H Sep 24, 2015 4:33 PM in response to thotter11
    Level 7 (21,825 points)
    Quicktime
    Sep 24, 2015 4:33 PM in response to thotter11

    Could you post a screen shot of a frame that shows these bands? Or even better, a link to a short section of the video.

     

    There are some contributors to the forum who know a fair amount about cameras and hopefully you'll get some ideas.

     

    Russ

  • by BenB,

    BenB BenB Sep 25, 2015 5:17 AM in response to Russ H
    Level 6 (9,936 points)
    Audio
    Sep 25, 2015 5:17 AM in response to Russ H

    Russ is correct, that could be a dozen different things.

  • by David Bogie Chq-1,

    David Bogie Chq-1 David Bogie Chq-1 Sep 25, 2015 7:37 AM in response to thotter11
    Level 7 (25,792 points)
    Video
    Sep 25, 2015 7:37 AM in response to thotter11

    Horizontal "light" bands. Do you mean these bands seem to be caused by lights (they're darker) or the bands are lighter than the rest of the frame? How tall are these bands? Do they migrate through the shot going up or down? Shutter speed mismatch is difficult to see when monitoring the live shot but it's immediately apparent in playback of a test exposure.

     

    The usual cause is shooting with a shutter speed that is inappropriate for the local mains. If you were shooting at 1/30 second under fluorescent or ballasted lighting that was fed by 50Hz mains, you're going to get a dark band that floats through your image. This represents the few scan lines that were exposed while the lighting instruments were dimming up or down.

     

    There is a filter in Adobe After Effects that can help with shutter speed/mans mismatching; I do not know if there is a similar filter in Motion.

     

    You could also be seeing a hum bar introduced into the video recording by improper electrical connections. Not likely these days but possible. You could be seeing a hum bar introduced by audio contamination. Again, not likely these days and you should have heard that much audio bleed in your headphones.

  • by thotter11,

    thotter11 thotter11 Sep 25, 2015 11:59 AM in response to Russ H
    Level 1 (0 points)
    Sep 25, 2015 11:59 AM in response to Russ H

    Here are a few shots!

     

    I was shooting in a 1/60 shutter speed but the lights were programmed at a variety of setting and I just couldn't keep up with them all. I do 99% of my work in natural light, I was trying to help out a friend and am still very new to the light designer music video style. Screen Shot 2.png

    Screen Shot 4.png

  • by David Bogie Chq-1,

    David Bogie Chq-1 David Bogie Chq-1 Sep 25, 2015 1:14 PM in response to David Bogie Chq-1
    Level 7 (25,792 points)
    Video
    Sep 25, 2015 1:14 PM in response to David Bogie Chq-1

    I was expecting to see something totally different. And shooting out of sync with lighting mains usually produces a ramping in the exposure, seen easily in playback. I was writing too quickly in my earlier response. One only sees bands of shutter speed artifacts when shooting something that is either being scanned, like a CRT. Sorry about the stupid confusion on my part.

     

    Anyway, what you've got there sure looks like your on camera mic was picking up the highly amplified PA and freaking out the video pickup. Used to happen in ye old analog days. Do you see these lines on a scope? Do they move up or down? Do they change in height or otherwise modulate?

  • by thotter11,

    thotter11 thotter11 Sep 25, 2015 2:53 PM in response to David Bogie Chq-1
    Level 1 (0 points)
    Sep 25, 2015 2:53 PM in response to David Bogie Chq-1

    They don't modulate with the sound, they just run up and down the screen. It was hard to notice while shooting because there were a lot of lights moving and I couldn't tell if I was just capturing the moving lights or if it was an error. And it only appears in half the video because the lights kept changing throughout so its only apparent with one of the light settings. I know in color corrector 3 way you could select the bands and adjust them and make them less noticeable, I have found plenty of tutorials on that, however none for final cut pro x which doesn't quite have the same set up.