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Sony A7s - Strange Light Banding

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dan hopkins
Sony A7s - Strange Light Banding
on Nov 25, 2014 at 3:02:04 am

Hey guys,

I've only been using the A7s for about 2 weeks now, and all of my initial tests were great. However, I just did a very basic documentary interview shoot and at first glance the footage looked fine. Then as I scrolled through quickly to find the parts I needed, I saw this very strange light banding effect occurring.. It looks like thick lines of white light slowly scrolling up through the image. This was filmed using Slog2 and I believe the Pro color mode. Frame rate was 23.976 with a shutter of 1/50... I hadn't seen this before with my own test footage, so I'm wondering if it's just something to do with the kind of light he had in his basement, I've also heard that Slog2 can cause this with certain lighting situations..? Here is a video sample sped up to show the effect more clearly. Take a look at what's happening on the wood grain wall behind him... Very curious as to what's going on... Thanks for your help!







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Steve Crow
Re: Sony A7s - Strange Light Banding
on Nov 25, 2014 at 7:45:51 am

I am ninety percent sure it is related to the lighting in the room, probably fluorescent, and the interaction between the cycle rate of your local power supply and the shutter speed. There have been several discussions of this on this forum that you should be able to easily find.

The issue in your particular clip is pretty subtle actually, I've seen much worse video clips here and elsewhere with ugly orange/brown or yellow bars crawling up the walls.

Steve

Steve Crow


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dan hopkins
Re: Sony A7s - Strange Light Banding
on Nov 25, 2014 at 5:02:33 pm

Thanks Steve,

I'm new to this forum, any chance you'd be able to help me locate this thread somewhere else on the site?

Thanks for your help,
-Dan


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Steve Crow
Re: Sony A7s - Strange Light Banding
on Nov 25, 2014 at 6:07:35 pm

You can start here:

https://forums.creativecow.net/thread/280/10581#10581

but just enter in keywords like fluorescent or banding into the search box and you should find more

Steve Crow


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dan hopkins
Re: Sony A7s - Strange Light Banding
on Nov 25, 2014 at 6:32:26 pm

Thanks! This was tremendously helpful. It's very hard to tell in the footage when it's playing out in regular time, so hopefully nobody will notice. Thanks again,
-Dan


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Kaileen Fitzpatrick
Re: Sony A7s - Strange Light Banding
on Dec 1, 2014 at 7:45:02 pm

i would try other Picture Profiles too. I ran in to situations where over exposed sections would turn to plastic much like this man's head. I was shooting in daylight too.....

just a thought.

Kaileen


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James Dow
Re: Sony A7s - Strange Light Banding
on Dec 3, 2014 at 7:14:30 pm

I had pretty much the same thing happen on my initial recording with my new A7s. I wasn't recording in S log 2, but it was definitely an artifact of the florescent lighting in the room.

JPD


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