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how would you do this effect?


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#1 Delorme Jean-Marie

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Posted 30 August 2005 - 04:10 PM

hi i have a new question, (i hope i'm not abusing of the kindness of the members of this forum)

i need to do a effect on a child face, it' s at night, outdoor, a flash lightning comming from what the child is looking at. He is actualy looking at a body surrounded by electricity, (like the dolorean in back to the future...)
i thought about turning on an hmi arc but i'm scared to be too green and hard to control.
how would you do this?
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#2 Stuart Brereton

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Posted 30 August 2005 - 05:06 PM

Assuming that you want a blueish lightning effect, and that your shot is at least an MCU, why not just flash a 650w or a 1k with 1/2 or full blue on it from the direction your actor is looking?

There are many ways of doing this effect, but I think this is probably the simplest.
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#3 Lars.Erik

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Posted 30 August 2005 - 05:36 PM

What about the company that has designed lamps just for these purposes?

http://www.lightningstrikes.com

Turning on a HMI arc will give a greenish light at first, as you stated.
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#4 fstop

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Posted 30 August 2005 - 05:58 PM

Listen to Stuart.

P.S: why do Lightningstrikes even bother sticking Beverly Hills Cop 3 on their credits list? :blink:
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#5 Luke Prendergast

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Posted 30 August 2005 - 06:30 PM

If it's just the child's face that needs illuminating I think Lightning Strikes would be way overkill. How about a cheap fluorescent fixture with a conventional blink-blink starter? It won't be a point source, which could help the gag, and the falloff will leave the background largely unaffected. You can syncopate your switch operation with the strike time of the tube for a continuous flickering.
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#6 David Mullen ASC

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Posted 30 August 2005 - 09:28 PM

I usually rent some metal venetian blind-type shutters from a lighting house and put that in front of an HMI... slap them open and close real fast & randomly.
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#7 drew_town

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Posted 31 August 2005 - 11:08 PM

I've used a photographer's flash before. It was cheap, fast, easy, and worked okay. The only thing I didn't like about it was that it was too fast (about 3 frames).
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#8 Bob Hayes

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Posted 01 September 2005 - 02:16 AM

If you want the effect to look like the lighting around the Delorean in ?Back to the Future? I think I?d bounce a couple of bright lights, 1K pars for example, with Full blue into some crumpled up shinny aluminum foil taped to a card board. Put the lights on dimmers so you can bring the electricity up from nothing.
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#9 Tomas Koolhaas

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Posted 04 September 2005 - 05:51 PM

Hello,
There are also many types of Flicker boxes for rent that have pre-set lightning settings which you can use. You could get one that has outputs for multiple lights which can be dimmed and set to trigger at different increments and for different durations, independent of each other, this may be the easiest way to simulate electricity flickering.
Cheers.
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#10 Glenn Hanns

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Posted 07 September 2005 - 05:43 PM

hi i have a new question, (i hope i'm not abusing of the kindness of the members of this forum)

i need to do a effect on a child face, it' s at night, outdoor, a flash lightning comming from what the child is looking at. He is actualy looking at a body surrounded by electricity, (like the dolorean in back to the future...)
i thought about turning on an hmi arc but i'm scared to be too green and hard to control.
how would you do this?

<{POST_SNAPBACK}>


Could try getting an arc welder and bouncing some of the strike back onto the face. Direct light might be too dangerous for talent so bounce it off some foil.
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#11 Robert Hughes

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Posted 08 September 2005 - 10:07 AM

In old Hollywood I believe they achieved lightning effects by momentarily striking carbon arc lamps. So the arc welder option should likely give a similar effect.
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#12 Dimitrios Koukas

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Posted 08 September 2005 - 03:39 PM

Lol,
Nice advises, most of them will do the effect, it's just what is the film sensitivity?
Are u shooting 25 fps? or 150 fps? Super duper telephoto lens or a high speed one?
Regards
Dimitrios Koukas
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#13 Kenny N Suleimanagich

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Posted 11 April 2007 - 08:18 PM

It might be a bit too much, but I know someone who used to handle scissor-arcs which are basically a bunch of positive carbons and a bunch of negative carbons, both charged with I BELIEVE 115V and then when you need the flash the scissors close and produce the huge flash. Its like when you're striking a carbon arc but much more and much quicker.
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#14 Jonathan Bowerbank

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Posted 11 April 2007 - 09:04 PM

I usually rent some metal venetian blind-type shutters from a lighting house and put that in front of an HMI... slap them open and close real fast & randomly.


It's interesting how so many people forget about those shutters, David. I suppose this day & age people automatically try and go for the more high technology way of achieving the effect...when really, it's been there all along. Tucked away in the annals of history, more specifically in Alton's "Painting with Light".
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#15 Kevin Zanit

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Posted 11 April 2007 - 09:44 PM

The shutters can work well, though I usually rent strobes called "AF1000s" or the older versions were called "Dataflashes" by High End Systems (formally Lightwave Research).

These are pretty cheap, DMX controlled, extremely high output Xenon strobes that can do constant output and everything in between. They rent for like $30 a day or so, I usually rent 4 of them with a DMX controller that is made for them.

Kevin Zanit
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#16 Nick Mulder

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Posted 11 April 2007 - 09:50 PM

I've used a photographer's flash before. It was cheap, fast, easy, and worked okay. The only thing I didn't like about it was that it was too fast (about 3 frames).

Are you talking about the ol' flaming napalm held above the photographers head ?

Flashes fire usually in the range of a factor of 10 to 200 times faster than an open shutter (24fps, 180deg) - ie. they can flash on and off many times whilst the shutter is closed and the film will never see it... (if it can recharge that fast and/or has a big cap reservoir to begin with).
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#17 Richard Andrewski

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Posted 11 April 2007 - 11:47 PM

The main problem with HMI's for this kind of effect is that they may not have hot restrike which means you have a period to wait before they'll turn on again. Of course, if you use the shutters in front of an HMI to achieve the effect, that's another story. Shouldn't have too much of a green spike after the light has been on a for a minute or so if the bulb is a good one.
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#18 Kenny N Suleimanagich

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Posted 12 April 2007 - 03:20 AM

why not just have a tungsten light with a macbeth glass instead of an HMI...
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#19 JD Hartman

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Posted 12 April 2007 - 08:55 AM

I'd have to agree with the suggestion to use shutters in front of the light source. Simple solutions usually work out the best. The old style carbon rod, lightning units were cabled to an arc welder (large DC power source). Elecric arcs produce ultra violet radiation in large quantites, not something you want near the talent or the crew. Welders call the resulting cornea burn, "sand in the eyes". Its temporary effect can last for up to 24 hours. Not pleasant.

Edited by JD Hartman, 12 April 2007 - 08:57 AM.

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#20 James Steven Beverly

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Posted 12 April 2007 - 05:51 PM

why not just have a tungsten light with a macbeth glass instead of an HMI...


what's a macbeth glass ?

what's a macbeth glass ?


Never mind, found it. Seen em before just didn't know what they were called.
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