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Old May 17th, 2003, 12:14 PM   #1
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Is Metal Halide the same as HMI?

Title says it all. I'm letting my obsessive/compulsive nature run wild again and I've decide I want to know everything I can about the technical side of lighting.

I'm finding companies that make pro-grade metal halide bulbs that have all different color temperatures with excellent cri numbers.

As an example. 4000k with 94cri in 250w... Thoughts?
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Old May 18th, 2003, 01:32 AM   #2
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No, they are different.

HMI's are alot more efficient than MH, I believe.

I don't see why you couldn't use MH lights, as long as you take the colour temperature into consideration.

One thing... Metal Halide ballasts are NOISY! They are commonly used for overhead lighting in warehouses and megastores (like Home Depot), and in streetlights. In a quiet area, you can hear them humming from a relatively long distance.
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Old May 18th, 2003, 06:05 AM   #3
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Matt...

Where are you finding these lights? Might be worth looking at.

Be aware that any arc light generates a heck of a lot of UV and some sort of effective UV filter will be needed to protect the talent and crew.

An extreme example is an arc welder. Same principal.

I once got a bad sunburn when welding steel as a teenager, not knowing any better. I wore the helmet and gloves, but no shirt. Wondered where I got the odd sunburn from until I realized it was where my skin was exposed to the arc!!

Lesson learned.

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Old May 18th, 2003, 07:34 AM   #4
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Dean, I've just been festering around for info on the net as I usually do.

I'm one of those obsessive compulsive types and the whole fluorescent thing is what started this for me. I was looking at the Kino and Lowel fluorescent kits and I haven't been able to figure out how they arrive at the super high prices. With fresnels and most openface lights I see a reasonable price/construction relationship... personally I think the LTM, Arri, Mole fresnels are a pretty good deal for what you get. And I think the Lowel openface lights are a good deal for the price and what you get there too... then we come to the fluorescents... what the heck is up with those? Over $1k w/o bulbs? I don't get it. No lens, no nothing... just a softbox by nature...

As it turns out good photo quality fluorescent bulbs can be had at less then $30 each.

Then some people get their eyes glazed over when they read "ballasts" and tech stuff... the reason CHEAP homeowner grade fluorescent lighting flickers is because it operates at 60hz... get a Super-Tek Electronic ballast and it operates at 60*Khz*... so NO flicker... one of those is less then a hundred bucks and often less then $75...

So the cost for ballast and case is what? $150? And then w/o bulbs they sell for $1K-$1,500? Seems kind of crazy to me...

DYLAN, the above ramblings leads me to the search for HMI info. I've been dissapointed at how little I've been able to find about HMI... I've found basically NONE... but when I search for it I always end up finding Metal Halide... so I thought they could be related.

With BOTH of these topics I want to tell you that it's not too hard to find bulbs in SUPER high CRI values and in almost ANY color temperature you want...

DYLAN has effectively shut down my interest in Metal Halide... THANK YOU for that! I have a bad habit of wasting my own time mindlessly determined to answer questions... I've seen exactly what you spoke of for myself... so Metal Halide is over.... although I should mention that you can get 250w Metal Halide bulbs with 4000k color and 94-96 CRI... so that should be a damn good bulb.

From what I understand a CRI of 100 is perfect and the color temp we USUALLY want is around 3200k... isn't that correct? I've also read that noon day sun is 5600k... so I'm assuming that we like the 3200k for it's slightly warming character? But wait! There's more! I've read that acceptable photo light starts in the mid to high 80's on cri... so anything in the 90's should be good and high 90's should be basically perfect. No?

You guys are great! Please offer some input on the fluorescent thread if you can...
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Old May 18th, 2003, 08:42 AM   #5
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Matt,

If your obsessive/compulsive nature has taken over and you've <<decide [you] want to know everything [you] can about the technical side of lighting>> ... then here's a brain-teaser for you.

Not long ago, I saw a highway crew here in Japan working at night using this one, amazingly brilliant light to see what they were doing. I've been wondering what type of light that was. It looked perfect for lighting night shots and getting a true moonlight effect.

Strange thing was, it was floating. No kidding. It looked like a chinese lantern made of some type of fabric, inflated like a blimp. It was moored with a couple of thin ropes or cables. The light-source was obviously centered inside and didn't flicker...and it cast this ultra bright bluish moonlight-blue hue in all directions. It was the brightest light I've ever seen.

It looked like the whole thing could be collapsed down to fit easily in the back of an SUV, but could light an entire set practically.

Anyone have any idea what that is?
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Old May 18th, 2003, 08:52 AM   #6
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It was godzilla

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Old May 18th, 2003, 08:55 AM   #7
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HMI is one of Osram's versions of metal halide lamps. Osram claims higher efficiency because of higher working temps (because of better sealings) and "hot restrike" properties. CRI is basically like all MH lamps.
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Old May 18th, 2003, 09:42 AM   #8
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So HMI IS metal halide? Which is it?

John, that sounds pretty wild. I have no clue what that could have been. I know the gas-arc lights are freaky bright. Unbelievable in person... but a blimp? Maybe a new product called the Tungstendenburg.

Andre... gimme' more! Do you have an internet source I can go to in order to find a graph of the emission characteristics? I found them on Kino Flo's web site for their fluorescents, but I haven't seen any graphs on tungsten...

The other thing to keep in mind here is that I will STILL get tungsten fresnels and maybe an openface, but since softlights are usually the most costly I'm doing this in an attempt to get the best possible product at the most reasonable cost.

I figure a good light kit contains at least two softlights and I can go traditional from there... also I like the idea of cutting heat wherever I can...
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Old May 18th, 2003, 11:55 AM   #9
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<<<-- Originally posted by Zac Stein : It was godzilla

Zac -->>>

LOL!


Matt, although Andre is right, he's not saying HMI is the same as MH.

Take a look at the bulbs. (using Ebay as a picture source)
HMI
Metal Halide

There may be hope for metal halides soon. Electonic ballasts have been made for them, and will probably hit the market soon. However, the bulbs are considerably larger, meaning a bigger light overall, so I don't expect to see any MH film/video lights anytime soon, if ever.

If you are a DIY guy, halides might be the best value for the dollar. You can get a 1000w bulb and ballast for less than $150. Just put the ballast in a different room from where you are shooting.
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Old May 18th, 2003, 12:11 PM   #10
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Just to let you know. I've already found electronic ballasts for metal halide lights at a reasonable cost. Also you can get metal halide bulbs down to 200w and lower... I don't forsee a use for too many 1k metal halide bulbs in my future. The wacky size of that 1k is because it's a 1k.

Also after researching this all morning I've found ballasts that are supposedly totally silent. Eventually I'll know if those manufacturers are full of crap or not... but I'd expect they would be begging for negative PR if they claim the ballast to be totally silent when in fact it was noisy.

At this point I still expect to go with standard tungsten fresnels... I'll see how the fluorescent experiment goes and then decide on this deal.

Thanks for all the help guys.
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Old May 18th, 2003, 12:14 PM   #11
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I want a couple HMI's, annybody suggest a decent one to look at, nothing outrageously priced please.

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Old May 18th, 2003, 12:48 PM   #12
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Matt, see http://www.soluxtli.com/edu9.htm for emission spectra.
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Old May 18th, 2003, 03:09 PM   #13
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Andre, I was excited to see that you could help me out on this, but when I went to your link I see that those graphs are lacking any source. There is a pretty big difference from one "daylight" fluorescent to another... using a graph to support facts without ANY explanation of where they actually obtained the numbers is worthless. It's too ambiguous... I'm sure that to some extent the general idea is the same but without reference it doesn't count.
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Old May 18th, 2003, 03:48 PM   #14
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Matt, I know there are differences. If you really want details I think you will need to contact manufacturers unless you have a spectrometer available. What are yr applications? My company (Barco) quite often needs detailed emission spectra for optimal color splitting filter design in projectors, but I don't think the very precise emission spectra for video/photo lighting are so crucial once you get 80+ CRI values specified.
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Old May 18th, 2003, 07:18 PM   #15
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A quick visit to this site: http://www.laserovashow.sk/balon3.htm should answer all your questions about the aforementioned "tungstendenberg".

also visit http://www.lightsup.net/film-set-new.html for more film related applications of this type of lighting
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