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Canon EOS Crop Sensor for HD
APS-C sensor cameras including the 80D, 70D, 7D Mk. II, 7D, EOS M and Rebel models for HD video recording.


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Old October 21st, 2010, 03:18 PM   #1
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Rolling lines on T2i

Hey guys, I was shooting some test footage last night at a club in the french quarter when these rolling lines started creeping into the lcd screen. They seem to get progressively worse as the shoot went on. My settings were 1080p 24 fps 1/50 shutter at 800 ISO using a Sigma 30mm 1.4 lens. I tried fooling around with the shutter and iso but the lines were still there. Any clues as to what this is and what's causing it?

YouTube - Rolling Lines on Canon T2i
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Old October 21st, 2010, 03:30 PM   #2
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What was the light source coming from the left side?
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Old October 21st, 2010, 03:30 PM   #3
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I've not even looked at your video......but I bet, from the description, it's the thing that gets posted about almost weekly.

In a 60Hz electricity supply country you need a shutter speed of 1/60th and in a 50Hz country 1/50th (or simple multiples of this) or the artificial lighting will do this to your video footage. Either that or (in a Club) a strobe light screwing things up in a similar fasion.
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Old October 21st, 2010, 03:34 PM   #4
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On his left were 4 flat blocks of white light that were on the wall. His back light was a z96 LED light.
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Old October 21st, 2010, 03:38 PM   #5
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I tried 1/60, it didn't work. No stobe lights were firing. It's like some sort of interference.

In a 60Hz electricity supply country you need a shutter speed of 1/60th and in a 50Hz country 1/50th (or simple multiples of this) or the artificial lighting will do this to your video footage. Either that or (in a Club) a strobe light screwing things up in a similar fasion.[/QUOTE]
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Old October 21st, 2010, 03:42 PM   #6
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OK, now you got me interested. Just looked at the video. Hmmm. Very strange - I have no clue what's happening here if 1/60th shutter speed did not work!
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Old October 21st, 2010, 03:42 PM   #7
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How close were you to a neon sign or CRT display?
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Old October 21st, 2010, 03:46 PM   #8
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You encountered the newer light that they use now a day, don't know what they are but I think some kind of led that they can change color instantly, I get that also even with 60th of a shutter in the US, you have to change your shutter to the extreme like maybe 30th or so, but once I got one that no matter what shutter speed I use I can only minimized it. Next time I run into this I will ask the lighting guy about it and see if he could somehow change frequency.
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Old October 21st, 2010, 03:50 PM   #9
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No CRTs were around, but I think there were some neon signs. They couldn't have been closer than 6 or 7 feet from camera.
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Old October 21st, 2010, 03:56 PM   #10
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Quote:
Originally Posted by Sean Woods View Post
No CRTs were around, but I think there were some neon signs. They couldn't have been closer than 6 or 7 feet from camera.
That's more than close enough. Next time, move about 2ft away, and then about 20ft away, and see if it affects your picture.
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Old October 22nd, 2010, 12:35 PM   #11
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I guess the next question would be is that are there any tricks in FCP or Premiere that I can do to make it seem less apparent or am I SOL?
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Old October 22nd, 2010, 12:53 PM   #12
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SOL as far as I know.
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Old October 23rd, 2010, 07:17 AM   #13
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SOL just about sums it up. Especially Sodium Vapour lamps found in big expo halls.

LED lamps are my favourite. They often pulse different groups on and off at high rates in order to achieve different colours:


I was also filming some automobile tail lights that were based on LEDs, which flickered with a similar look, didn't fit at either 1/50th or 1/60th, so had to use the ESC (Electronic Shutter Control) usually used for taming the bars on old CRT screens. Ended up on something like 1/57.358.

Usually turning the shutter OFF can quieten the effects if you don't have time to tame it via the shutter (or just plain can't). Depends on the flickering source.

Edit: Just remembered I'm in the T2i forum, rather than EX1! Yup, SOL.
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Old October 23rd, 2010, 08:20 AM   #14
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alot led lights uses Pulse Width Modulation (PWM) on their circuits for dimmimg the brightness.

Pulse-width modulation - Wikipedia, the free encyclopedia
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Old October 25th, 2010, 10:38 PM   #15
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if that was available light, I'd suggest the problem is 60hz flicker, but that you have 2 + light sources on difference phases of power inter modulating with each other making for extra weird. 1/30th would of fixed it for sure, just by leaving the exposure open long enough to even things out. I've done some HMI flicker tests and the faster you go, the worse it gets until you can have a very distinct bar moving thru the shot. any sort of high speed "flicker free" dimmer using PCM could also do this - at least FF designed for consumer purposes. I haven't tried shooting dimable flo lights, but they probably also make similar effects
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