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High Speed video lighting


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#1 John Draus

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Posted 17 February 2011 - 07:08 PM

Got a shoot coming up where they plan to shoot 2000fps video. Any problem with the light from 1200 watt Arri HMI's with electronic ballasts? Any thing else I should be aware of? Thanks.
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#2 Shidan Saberi

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Posted 17 February 2011 - 11:08 PM

Got a shoot coming up where they plan to shoot 2000fps video. Any problem with the light from 1200 watt Arri HMI's with electronic ballasts? Any thing else I should be aware of? Thanks.


Just out of curiosity what camera will you be using?
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#3 John Draus

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Posted 17 February 2011 - 11:14 PM

I don't know, yet. The PM who called me about supplying the lighting gear didn't know. They requested 2 1200 HMI's. I'm not sure how much the DP knows and I have no high speed experience beyond 60fps. I only found one relevant post when I searched the forum and they mentioned that there could be so issues.
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#4 Shidan Saberi

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Posted 18 February 2011 - 09:09 AM

I don't know, yet. The PM who called me about supplying the lighting gear didn't know. They requested 2 1200 HMI's. I'm not sure how much the DP knows and I have no high speed experience beyond 60fps. I only found one relevant post when I searched the forum and they mentioned that there could be so issues.



I really like slot motion. I remember watching a video on lighting and slow motion on youtube but i couldn't find it for you.

How far are your lights from the subject. Because at 2000fps they must be very illumined.

At such high speeds i would personally only use the suns light out doors or try and light it up that much.

If i were you i'd try to shoot under sun light or if that is not the option perhaps try to get a hold of the camera in advance and try those lights out. That way if they don't work you'll have a week or a day till the shoot and you'll see how much more light that camera actually needs and be able to prepare for it some how. Perhaps by renting another stronger light.

Also if you can get a cheap light meter (from $10 of ebay) and use that to work out how much light you need. Test how much light is on your subject outdoor and try to match that with lights indoor.
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#5 Mitch Gross

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Posted 20 February 2011 - 12:14 AM

Stay away from HMIs for high speed work. A very high frame rates, a condition called "Arc Wander" can be observed. This is where the plasmatic electrical lode moves from one electrode to the other inside the glass envelope of the bulb, causing not quite a flicker but more of a shimmering effect. It is very problematical in the image and is impossible to predict.

Best solution for high speed is very large tungsten fixtures (2K and above in 60hz countries, 5K and up in 50hz countries). Even on AC power these won't flicker as the filiaments will be so hot that they just won't have a chance to cool between cycles. The other option is finding true DC power (not just rectified power), which will simply leave the light hot all the time. This can be very hard to come by and is in fact illegal in many areas.
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#6 Mathew Rudenberg

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Posted 20 February 2011 - 03:20 AM

Stay away from HMIs for high speed work. A very high frame rates, a condition called "Arc Wander" can be observed. This is where the plasmatic electrical lode moves from one electrode to the other inside the glass envelope of the bulb, causing not quite a flicker but more of a shimmering effect. It is very problematical in the image and is impossible to predict.


Do you think arc wander would be less of a problem if you're using heavy fairly diffusion? I would imagine that the slight variation in the position of the point source would be hidden by a larger surface...
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#7 aapo lettinen

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Posted 20 February 2011 - 08:12 AM

I found this article interesting, maybe you want to read it too (for a lighting reference etc)
http://provideocoali...ps_on_a_budget/
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#8 John Draus

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Posted 20 February 2011 - 12:55 PM

Hi all,
Thanks for all the input. I'm working as the gaffer on this shoot and I forwarded the info on arc wander to the production Mgr that hired me. I'm not sure what they are thinking, who the DP is and what size their shots are, but it sounds like a large shot to me. All they are asking for light wise are a couple of HMI's and some kinos. They originally asked for 1200 HMIs but are thinking of using 575s instead. We are shooting in a warehouse. The scout pics I saw looked like sodium vapor lights or maybe metal halide. Sounds like it's going to be a mess.
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#9 Mitch Gross

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Posted 20 February 2011 - 11:14 PM

Do you think arc wander would be less of a problem if you're using heavy fairly diffusion? I would imagine that the slight variation in the position of the point source would be hidden by a larger surface...


It will certainly help mitigate and possibly eliminate the issue. But it will also cut down the light, which one always needs on a high speed shoot.
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#10 Mitch Gross

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Posted 20 February 2011 - 11:19 PM

Hi all,
Thanks for all the input. I'm working as the gaffer on this shoot and I forwarded the info on arc wander to the production Mgr that hired me. I'm not sure what they are thinking, who the DP is and what size their shots are, but it sounds like a large shot to me. All they are asking for light wise are a couple of HMI's and some kinos. They originally asked for 1200 HMIs but are thinking of using 575s instead. We are shooting in a warehouse. The scout pics I saw looked like sodium vapor lights or maybe metal halide. Sounds like it's going to be a mess.

Sounds like they have no clue what they're getting into. Those sodium lights will be freaky at off speeds.

For more info take a look at our high speed FAQ, which has a section on lighting near the end.

http://www.abelcine....id=42&Itemid=57
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#11 timHealy

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Posted 25 February 2011 - 11:20 AM

I haven't done a lot of high speed work, but what I have done and have been told by friends, light levels will be the huge issue. 2 -1200 watt pars will be insufficient. I have one friend who did a shot of a bottle of Disani water dropped into water at an extremely high frame rate and f stop. They used something like 18 tungsten 20k's and they used one of them full up on the dimmer as the background. Not the background light, the shot directly into the light. You may not need something so extreme, but I hope you get the point.

Best

Tim
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#12 John Draus

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Posted 25 February 2011 - 12:29 PM

Well, we shot yesterday and everything turned out fine. They shot at 1000fps, not sure what shutter speed, using a MEC camera, not sure of the model. using a 1200HMI PAR w/ electronic ballast they shot at T3.7. If there was any "shimmering" or "arc wander" it was not too disturbing, at least not on the laptop window. No complaints from the client anyway. Had to put a spot lens on the 1200. to give them any depth of field. But, all's well that ends well.
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