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Metal Halide


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#1 Richard R. Robbins

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Posted 23 February 2006 - 02:10 PM

Hello to all, first post...
I've been having this thought about installing a 400 watt Metal Halide globe (with ballast) into a 2K sized fresnel fixture. You know, an outdoor yard/farm light. I'm dreaming the result would be a daylight balanced source which would be focusable/controllable. It would be very bright and only draw 3 1/2 amps. I shoot now almost all digital video (SDX-900). Any thoughts?
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#2 Matt Sander

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Posted 23 February 2006 - 02:47 PM

I would check the color temperature of the bulb often, all of the Halides I have used seem to drift away from their original temperature pretty fast.
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#3 Luke Prendergast

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Posted 23 February 2006 - 04:16 PM

drift away from their original temperature

They drift in color temp over their (x0000 hr) life, or is it short-term wandering, ie., unstable color temp?

I've used only 150w MH fresnels and the light output is way more than a 650w tungsten fixture, and their 4000k only needs 1/2 CTB to get in the region of daylight.
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#4 Dominik Muench

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Posted 23 February 2006 - 04:47 PM

dont they have a greenish color ? or do i mix that up with silver halide bulbs that are often used in sport arenas ?
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#5 Patrick Neary

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Posted 23 February 2006 - 05:47 PM

Hi-

Silver Halide isn't a lamp, it's what's in your emulsion :)

The kind of metal halide sports arena lighting I've encountered is generally blue-ish with at least some component of yellow/green. I was scouting a softball field recently and got all excited when I saw that the lighting fixtures surrounding the field were Musco lights (sportscluster 2s) but quickly discovered they're not quite the same units as the big film lights! They were certainly bright enough, at about 50+ footcandles anywhere on the field, but a quick (digital) stills test showed a small bit of yellowish-green, nothing that couldn't be corrected out pretty easily though. Well, more easily than lighting the entire field from scratch.
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#6 Dominik Muench

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Posted 24 February 2006 - 04:59 AM

Hi-

Silver Halide isn't a lamp, it's what's in your emulsion :)

The kind of metal halide sports arena lighting I've encountered is generally blue-ish with at least some component of yellow/green. I was scouting a softball field recently and got all excited when I saw that the lighting fixtures surrounding the field were Musco lights (sportscluster 2s) but quickly discovered they're not quite the same units as the big film lights! They were certainly bright enough, at about 50+ footcandles anywhere on the field, but a quick (digital) stills test showed a small bit of yellowish-green, nothing that couldn't be corrected out pretty easily though. Well, more easily than lighting the entire field from scratch.



*Lol of course...sorry...i meant sodium vapour lights, i always mix that up *blushes
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#7 Matt Sandstrom

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Posted 24 February 2006 - 08:13 AM

um, are you sure you're not mixing it up again? sodium vapor is orange/yellow afaik. ;-)

/matt
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#8 Phil Rhodes

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Posted 24 February 2006 - 10:12 AM

Hi,

Saying "Metal Halide" is as ambiguous as saying "fluorescent tube." They can be any colour of the rainbow and any shade of non-white you happen to fancy. Practically any type of discharge lamp except an HMI or Xenon is usually a metal halide lamp.

MSR is OK, and tends to be about 4000K, making it filterable to either tungsten or daylight without too much loss. They're readily available.

Phil
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#9 Hal Smith

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Posted 24 February 2006 - 10:52 AM

Hi,

Saying "Metal Halide" is as ambiguous as saying "fluorescent tube." They can be any colour of the rainbow and any shade of non-white you happen to fancy. Practically any type of discharge lamp except an HMI or Xenon is usually a metal halide lamp.

MSR is OK, and tends to be about 4000K, making it filterable to either tungsten or daylight without too much loss. They're readily available.

Phil

My Cyberlight Lithos run MSR1200/2's. They're 7200K, a bit bluer than daylight. They have a CRI of 85.

Bulbman has a product listing for MSR's at: http://www.bulbman.c...ndex&cPath=6191 . Each lamp has a link to a specifications page.

Each MSR lamp has several variants with respect to color temperature. There usually is a variant with a color temperature of 6K which nominally matches HMI's CT of 6K.

Still photographers that have taken photos of my Cyberlights in action usually have come up with rather cold looking prints if not corrected in their versions of post. Video usually looks okay if white balanced. But when mixed with 3200K halogens, my Cyberlights look very much like very old fashioned arc spotlights - they're good for followspot and/or special effect looks but nothing else! No motion picture film has been shot of my lights but they will definitely look bad on tungsten films and somewhat blue on uncorrected daylight film.

There's a whole other issue with MSR and HMI. Their spectrums are not continuous - all gas arc light lamps have "liney" spectrums. That can be a REAL bugaboo trying to color time for a specific look. Labs have a lot of experience with HMI color timing, they know what to do. I'd advise research and testing before you invest a lot of time and money using MSR's to light film. The only way I'd jump into MSR's is with the 6000K variants and only after checking with Osram, GE, etc to see if the spectrum of 6000K MSR's is identical to 6000K HMI's. You'd be on very thin ice with any lamp with a line spectrum other than what HMI's have. I don't know exactly how much trouble you'd have but there is a very good reason why Cinema technology tends to be very conservative - it's not just a matter of reinventing the wheel - it's a matter of just how expensive that new wheel may be after you've fixed all the new problems it's created!

John Pytlak probably has some very pithy comments to make about all this, are you lurking John?

Edmond, OK

Addition: The posts talking about strange tints, etc. are reflecting all my gab about "line" spectrums and color temperature. The interaction between the line spectrum output of a given gas mixture versus the light color bandpasses of color film's color separation layers is very complex. I don't know for a fact that HMI's were developed with specific color film spectrum responses in mind, or whether or not Kodak and Fuji actively develop films with HMI characteristics in mind but I would be very surprised if they didn't at all. I'm not the only person working with film who has a Master's Degree in Physics who did their graduate thesis on Spectroscopy. Kodak and Fuji probably both have labs with Physics PhD's underfoot. :)
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#10 Dominik Muench

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Posted 24 February 2006 - 11:01 AM

um, are you sure you're not mixing it up again? sodium vapor is orange/yellow afaik. ;-)

/matt



hmm ok i better shut up now :)

i once had this shoot in a carwash which was lit with huge lighst that had a really greenish tint, and i could swear the owner said that those were sodium vapour, but he probably knew as much as i do about those lights :)
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#11 Patrick Neary

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Posted 24 February 2006 - 11:10 AM

The AC Manual has a good chapter on industrial lamps and their characteristics and suggestions for color correction.
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#12 Richard R. Robbins

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Posted 24 February 2006 - 12:06 PM

Well, how interesting it is to ask a question and receive so many replys!
Um, back to my original question...
Doesn't anyone agree that having a bright (close to) daylight balanced fixture which draws little current could be a cool thing? (no pun intended) The only real downside that I can think of is that once you stike the lamp (turn it on), if you shut it off...you're gonna have to wait for a while before it will come back up to speed. As in, "Let's key from the other side...unplug and move that light over here...whoops, it'll be about 10 minutes til that light is back up, sorry." I've had to shot under metal halides alot, both film and video, and I've found that if you white balance properly (or shoot a chart for the colorist), the image will be just fine. What do you think?

PS...What is an MSR light? Matthews Stand Reflector, Mole Standard Richardson, Metal Silly Redo?

Rich
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#13 Phil Rhodes

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Posted 24 February 2006 - 02:04 PM

Hi,

"Medium (arc) Source Rare earth" is the definition usually given, but I have a feeling this may be an apocryphal assumption. Certainly they're medium-arc lamps.

Depending on what "rare earth" (lanthanide, etc metal salts) are used the CT will vary.

Phil
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#14 Hal Smith

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Posted 24 February 2006 - 03:51 PM

Hi,

"Medium (arc) Source Rare earth" is the definition usually given, but I have a feeling this may be an apocryphal assumption. Certainly they're medium-arc lamps.

Depending on what "rare earth" (lanthanide, etc metal salts) are used the CT will vary.

Phil

That's the definition I've seen in manufacturer's literature.

There's some illumination ;) on MSR,HMI, etc. vs. Tungsten at

http://www.highend.c...g/colortemp.asp

They don't address film but there is a good graph illustrating arc vs incandescent light sources.
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#15 Mike Hall

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Posted 24 February 2006 - 07:36 PM

I don't think you'll have any problem with one. However, if you are going to make a couple of these up as a kit, you will more than likely have to try several bulbs to get say, three to match closely. Most industrial bulbs are not matched for color in the mfg. process.

There is the usage question: if you are just going to use this one lighting something inanimate, probably not a bad idea. However, if you are planning on taking one or more around and using them on people, then you may want to think twice. If, for whatever reason, something goes horribly wrong, and you have to tell a judge (or an insurance inspector) that you just made the light at home because it sounded like a cheap alternative to HMI's and you never thought it would blow up and harm someone, things could get expensive anyway.

I think I would look for an industrial light that is meant to be transported, and go from there. More than likely if there is something that can go horribly wrong with the fixture they will either warn about it on a label, or have a way to prevent the lamp from working unsafely (like micro-switches on HMI's).

Anyway, a couple of devil's advocate thoughts.

"It's all fun and games 'till somebody loses an eye; then "sorry" is just not enough".

Edited by Mike Hall, 24 February 2006 - 07:41 PM.

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