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Practical flourescent fixtures flickering HELP!!


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#1 Matt Cabinum

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Posted 21 July 2007 - 04:25 PM

Does anyone have any knowledge on how to get a flouresent fixture to flicker. Not a pulsing or a strobe but a completely random flicker. I have to get the fixture to do this while being in the shot. Does anyone know of any household rigs that can be used or any commercial rigs that can be used. I have heard people say that loosening the bulbs should work but that is not controllable. I am looking for control over the flicker while keeping it completely random. Any and all suggestions would be extremely benificial. Thank you for your help!
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#2 Kevin Zanit

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Posted 21 July 2007 - 05:00 PM

How can you control an effect that is "completely random"?

Putting the fluorescent on a dimmer usually works, however usually also ruins the ballast.
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#3 timHealy

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Posted 22 July 2007 - 12:29 AM

I'm far from a dimmer board expert but I'm sure there is a way to do it via a software base dimmer system like

http://www.lanbox.com/

or I wonder if a Magic Gadget or Shadow maker would be an easier one light fix.

Best

Tim
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#4 Jonathan Bowerbank

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Posted 22 July 2007 - 03:11 AM

I am looking for control over the flicker while keeping it completely random.


Read that sentence to yourself, as many times as needed, ha ha.

If loosening the bulb works and looks good, then go for it...just not so loose it falls and shatters in someone's eyes.

I used to have some CFL's at home that were hooked up to a toggle dimmer switch, and when I dimmed down they gave a really cool flicker which I did to bug my wife sometimes. You might wanna consider something as simple as that.

Edited by Jonathan Bowerbank, 22 July 2007 - 03:11 AM.

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#5 Kenny N Suleimanagich

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Posted 22 July 2007 - 04:58 AM

If you're using Kino Flo's you could just have someone control it from the ballast with the dimmer and/or switches if theyre quick enough.
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#6 timHealy

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Posted 22 July 2007 - 11:18 AM

Why are you guys poking fun at him?

Giving something a random quality and controlling the parameters of it, is something is that is completely legitimate and reasonable.

And using whatever device he finds to keep that randomness "consistant", may be important during the course of a scenes shooting whether is takes half a day or a week.

I have done human switching on and off, to create a multitude of effects, and sometimes it works and sometimes it doesn't. Sometimes you don't know that it doesn't work until editing two shots together and you can see with the human factor has changed between shots. Giving control to a dimmer board, variac or some other device is the best way to go.

Best

Tim

Edited by timHealy, 22 July 2007 - 11:23 AM.

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#7 John Brawley

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Posted 22 July 2007 - 11:29 AM

If you're using a regular flouro fixture, you can just change in a dodgy starter motor. Some gaffers I've worked with have a collection with them for just this thing. Otherwise simply turning the ficture off an on can work pretty well.
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#8 Jonathan Bowerbank

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Posted 22 July 2007 - 05:56 PM

Why are you guys poking fun at him?


We all know what he meant, it was just the wording with "keeping it completely random", sounded funny, ya know?

Of course he can have full control over how random he wants his light to appear...perhaps it wouldn't have sounded so funny had he written that, "to APPEAR completely random."

:)
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#9 John Sprung

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Posted 24 July 2007 - 12:59 PM

I've done that simply by rigging up a push button switch in series with the light, and having a guy with a twitchy thumb play with it like a Morse code key.



-- J.S.
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#10 Phil Rhodes

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Posted 24 July 2007 - 02:48 PM

This can be difficult, regardless of how you control it. As the lamp warms up, which it will do quickly if it is being started a lot, it will react differently to the same input, generally being easier to start and therefore "on" more. So, even if you have a clever controller applying a clever pseudo-random flicker to the thing, it is unlikely to remain stable. Worse, it may change its characteristic subtly but slowly as it warms up, resulting in a matching problem you won't notice.

For these reasons, I advocate the manual control approach. When I've done this, I've always just had someone wiggle the plug in the socket; that way, it's really controllable, based on how much light the operator sees coming out!

As a side note, you are likely to stress the lamps and starters quite highly, especially if you do it for a long time. Both are cheap enough to be treated as expendables, but certainly here, and I suspect in green-happy California, there will be disposal rules for the lamps. They contain toxic heavy metals and should be sent to a good home, both to avoid pollution and to allow these exotic materials to be reclaimed.

Phil
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