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Another Metal Halide Question

lighting metal halide

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#1 Victor Bareno

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Posted 06 April 2013 - 09:44 PM

Hello, I've been scouring for some info on the usefulness of these lights, and found a variety of answers which haven't answered everything yet.

 

I noticed there are some metal halide lamps for sale locally.

 

http://tucson.craigs...3725934718.html

http://tucson.craigs...3726091526.html

 

For $45, 1000w of that type of light must be very powerful. It's the one I'm primarily interested in. I like to rely as much on my tungsten I can. But I only have up to a 2kw which could probably handle backlight well, but not much else, plus, what if I have a larger area and I need a stronger rim of light, etc..

I have little experience lighting this style... I admire the look on "Last of the Mohicans" as it's very natural and convincing, yet there is obviously powerful lights.

 

1:07 is a great look.

 

I can see it would require 2 units for the kicker (or is it rim?) and top light, which is not actually natural, yet it still looks absolutely convincing because the top appears to come from the kicker's direction. Another unit for the fill, and I think a little white edge light to motivate the fill. I am wondering if similar results could be had with the likes of 3-4 1kw MH lights arranged properly.

 

These lights are appealing because they are dirt cheap compared to HMI's, and even with a 4000k temp, it leaves room good room for temp changes. I don't know what type, if any, color casts will be involved, I speculate +magenta might help if so? Again, I don't know how useful or practical such lamps may be. Another issue is mounting.. how the heck would I stick one on a stand? They're meant to be "bay lights".

 

If everything is out the window, I would hope at least some of the smaller units (400w or 250w) would serve as good practicals in an urban setting, not necessarily doing much illumination. I have seen this done and it typically looks more cyan than blue, which makes me wonder how to get it true blue. Terminator 2 also used MH's I believe, and it added to the cold, already cyanic atmosphere.

 

Thanks for all the help.


Edited by Victor Bareno, 06 April 2013 - 09:47 PM.

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#2 Phil Rhodes

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Posted 07 April 2013 - 01:47 PM

They're designed to be hung from the beams supporting the roof of a warehouse or factory. There's probably no reason you couldn't work out some sort of mounting arrangements for them, although make sure they're happy being run at angles other than the vertical. A minority of lighting gear is designed to be run in only one orientation with respect to gravity for cooling or arc stability reasons, but that's pretty rare.

 

Edit - oh, there you go, the orientation limit is printed on the ballast. Read and evaluate.

 

They're probably mercury vapour, which looks white to the eye and typically slightly turquoise or cyan to video cameras. This is actually quite an interesting option if you're into embracing the colour casts of mixed-source lighting, and I wouldn't mind having something like that for that reason alone. You could evaluate what filtration would be required; of course, filtration reduces efficiency.

 

They're almost certainly iron ballasts and will therefore flicker at the 60Hz (where you are). The importance of this varies with the application. Often you can trim it out with careful shutter speed selection. If you want to shoot high speed (say, with an FS700) you'd have to avoid these lights. They will probably take a minute or so to warm up, and may not like restarting while hot. Cooling down may take ten minutes, and the no-hot-restrike problem is one of the principal issues with using industrial metal halide lighting for film and TV work. Then again, many older HMIs have exactly the same problem (they're also a type of metal halide light).

 

Hope this helps,

 

P


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#3 Stuart Brereton

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Posted 07 April 2013 - 02:05 PM

In addition to what Phil said, 2 other issues may arise.

 

1. You may find it impossible to properly correct these lamps to 'white'. These lamps are not continuous spectrum, and so correcting the green spike will still not give you white light, as other light wavelengths may be missing entirely.

 

2. The ballasts for these lamps are often very noisy, which could be a problem if you're shooting with sync sound.

 

As Phil said, if you embrace the limitations, they are probably quite fun to have on the truck.


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#4 Victor Bareno

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Posted 14 April 2013 - 12:48 AM

Thanks Phil & Stuart for the insightful information. I plan to use these with a standard 180 shutter, so I don't believe flicker issues will arise.

 

I understand they are not continuous spectrum; however is this not the case with your run-of-the-mill HMI's? That's unfortunate, but if a good exposure is produced, and I can have some control, then they do seem like a good source to use at night. I can vaguely see the difference between a good continuous source and one that isn't. It's rich, but at night, I don't feel one requires that same level of richness, unless you're in Hollywood, of course... :-)


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#5 Stuart Brereton

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Posted 14 April 2013 - 08:37 PM

I understand they are not continuous spectrum; however is this not the case with your run-of-the-mill HMI's? That's unfortunate, but if a good exposure is produced, and I can have some control, then they do seem like a good source to use at night. I can vaguely see the difference between a good continuous source and one that isn't. It's rich, but at night, I don't feel one requires that same level of richness, unless you're in Hollywood, of course... :-)

HMIs have a high CRI (Color Rendering Index), generally 90+. Industrial discharge lamps don't. Mercury vapor will have a green spike, sodium will have an orange spike. These will probably be impossible to correct entirely.


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#6 JD Hartman

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Posted 09 July 2013 - 09:22 PM

Shot with a low budget Producer and DP.  DP borrowed some 1500w MH stadium lights.  Insisted that most of the entire film could be lit with them as Shane Hurlbut had used and therefore....blah, blah, blah.....  My experience was they weren't very directional, basically a scoop type light, no barn door, no focus, etc., very hot, noisy ballast, heavy.  So heavy, that I had to call Mole-Richardson to get a maximum weight capacity figure for some of their junior grip equipment.we used to rig them.  Expect to use lots of flags and diffusion.


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