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Light Flicker


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#1 Evan Andrew John Prosofsky

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Posted 02 October 2012 - 12:39 PM

Hi all!

I have a shoot coming up where the director would like to accentuate the harsh flourescents. Ideally they will be flickering like crazy and as ugly as possible. Think 8 mile. Now, I understand that flicker can be caused in camera (by shooting off speed) or by the actual light itself. I have seen flourescent lights flickering with my own eye, but can other lights flicker as well? (tungsten? mercury vapor? metal halide?)

So I guess my question is, what would the best approach be if I want to ensure the light is flickering on film? (We are shooting 5219). Should I shoot at an off speed (it is a music video so it doesn't matter) or can I "trick" the light to do this? Ideally I can get the light to do it as well so that if the dir. wants to we can shoot at safe speeds as well (eg. real time, 24fps).

I have attached an example video shot by the ridiculously talented Matthew J Lloyd CSC for Flying Lotus "Until The Quiet Comes". You see the effect very strongly at 1:44 and at 2:18 onward during the dance scene. Do you think he was just shooting at 32fps or something "inbetween" that allowed for flicker?
FLYING LOTUS -- "Until The Quiet Comes"

As always thanks so much for your help!
xx Evan
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#2 Igor Trajkovski

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Posted 02 October 2012 - 03:59 PM

I remember a good article by Art Adams
on PROVIDEO COALITION on how to avoid flicker.

He explains the "anatomy" of flicker and the effect on
global shutter camera and rolling shutter camera.

Film camera and flicker is mentioned also.


Link to article: Rough Guide to Flicker-Free HD Shooting


By knowing how to avoid it, you'll know how to create it. :)


Best

Igor
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#3 Cory Lonas

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Posted 04 October 2012 - 04:35 PM

I did this once by using a Diva Light and a an electronic dimmer. Most Flourescent fixtures will flicker when you decrease the input voltage if you don't want to risk messing with a Kino flo you could always go buy some CFLs or standard Flouro fixtures from home depot and run them through a a variac dimmer to try to find the sweet spot with the voltage where it flickers inconsistantly.
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#4 Mathew Rudenberg

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Posted 04 October 2012 - 07:46 PM

Shooting offspeed is the easiest way to get a fast constant flicker. This looks to be what happened in the video you referenced.

Many flourescent/ LED / and arc lamps will flicker if you shoot off speed. The slower heat up and cooldown of tungsten lights tends to hide the flicker until you get up to about 100 FPS. The best way to know is to test of course.

If you don't have access to the power supply of the lights you basically have two options: shoot off speed or flicker the lights in post.

If you do have access to the power supply you have a couple more options.

A standard dimmer does work, but in my experience I find it tricky to use because there is a very narrow point that flickers between completely on and off. Not only that but it varies, and you'll kill the ballast after a certain period of time.

I've had the most success just using a flicker box so you can dial in the exact level of flicker you want. Have fluorescent tubes and fixtures though, because this also kills them sooner or later.
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