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HMI vs. tungsten


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#1 Marc Levy

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Posted 28 June 2007 - 01:01 PM

Hello all,

A topic that always seems to cause me some apprehension while formulating my g/e lists is whether to lean toward HMI or tungsten lighting - especially when the shoot has a good bit of location day interiors with visible windows. HMI's are always my first instinct. Thus, I usually end up renting a package made up mostly of HMI's and Kinos (with both tungsten and daylight tubes), and a few tungsten heads, with the idea that I can always gel the HMI's down to 3200K or warmer if necessary, and I have more punch than the tungsten counterparts.

But I have noticed that I don't like the quality of light produced by HMI's as much as tungsten. It's something I can't put my finger on - maybe it's just a bit harsher, even when softened by the same diffusing methods. Maybe I'm imagining this - I don't know.

So, my question to all of you is, for shoots with a good bit of location day interiors, do you prefer HMI's or tungsten as the main source to emulate daylight and sunlight? (I'm not interested in gelling/diffusing techniques to match sunlight/daylight, etc.).

Thanks,
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#2 janusz sikora

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Posted 28 June 2007 - 01:13 PM

HMI is harsher... you are right. But this you know how to deal with. I had exactly the same uneasy feeling about quality of HMI light. It is the color... this mixture of Yellow Green in the skin tone... color of a dead body (hm) Once I started putting UV gel over the fixtures it improved tremendously. Some people say that added color correction eliminates UV leak... I found this not true... it still leaks. So I always use UV gel.
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#3 Richard Andrewski

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Posted 28 June 2007 - 07:19 PM

Most of these HMI's should have protection filter glass on them but some don't. That's why its a good idea to use the Rosco Cinegel #3114 like mentioned above.

http://www.rosco.com...ers/cinegel.asp

It filters 90% of all UV (UV being that spectrum below 390nm) light so its safer for talent.
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#4 Jonathan Bowerbank

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Posted 28 June 2007 - 10:37 PM

Nicola Pecorini had a great quote in a past issue of AC mag about the making of "Tideland". He expressed his opinion on HMI's, and how artificial they look. Incandescent tungsten lights, he feels, emulate the sunlight look much better because it's an actual burning source. If he could, he would use carbon arcs...but it's just not practical anymore.

Here's a link to a previous discussion over the ACL lights he (and Storaro) prefer: http://www.cinematog...=landing lights
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#5 Richard Andrewski

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Posted 28 June 2007 - 11:51 PM

I wonder how really different they are in effect from each other. The HMI and all metal halides are really like a "solid state" arc spot in the effect they produce. All modern spotlights use HMI or its derivatives and I wonder whether you can really see so much difference between the two. Both are blindingly bright, burn at incredible temperatures and emit lots of harmful UV too. You can't look directly at either of them without protection or risk being affected permanently.
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#6 Rob van Gelder

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Posted 02 July 2007 - 03:40 AM

Most of these HMI's should have protection filter glass on them but some don't. That's why its a good idea to use the Rosco Cinegel #3114 like mentioned above.

http://www.rosco.com...ers/cinegel.asp

It filters 90% of all UV (UV being that spectrum below 390nm) light so its safer for talent.



Any HMI that has no official Schott-glass UV protection in the lamphead should be trashed!!

The Arri factory had once a great example of what a HMI can do to the skin: a 400Watt HMI was used to light the Swedish King once during an interview.
The next day the king had a complete blistered face! I have seen the pictures of this! It turned out that the someone had "repaired" the little HMI and used normal glass instead of the special Schott-glass, with this result!

You can imagine what can happen with serous high wattage lamps that have no protection! You can die from them, just by the radiation!
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#7 Alexandre Lucena

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Posted 02 July 2007 - 09:22 AM

Hi,

Has anyone ever tried HQIs lamps as an alternative to HMIs?

Alexandre
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#8 Richard Andrewski

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Posted 02 July 2007 - 10:20 AM

Hi,

Has anyone ever tried HQIs lamps as an alternative to HMIs?

Alexandre


Hi Alexandre,

I've been working on this type of thing a lot since last year. You can read about it in my Blog. The answer is yes and they work fine. Ceramic metal halide is another very interesting technology that's even more advanced than HMI and older metal halide families in lifetime, color rendering and even ability to have a decent tungsten color with a high CRI.

http://www.coollight...tegory/articles

I wrote this multi-part series showing how you can convert an old fresnel to a metal halide / HMI type for under $500. Coincidentally with all this, I've been working on product development for my company with a lower cost line of HMI's to compliment our Softlight series of fluorescent fixtures. The articles have been designed to raise awareness of many of the issues around HMI / metal halide, why it's been so expensive in the past and why it doesn't really have to continue being expensive unless you chose for it to be.
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#9 Alexandre Lucena

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Posted 02 July 2007 - 03:55 PM

I wrote this multi-part series showing how you can convert an old fresnel to a metal halide / HMI type for under $500.


Great. Now I know what to do with a couple of 1k Mole Fresnels that are collecting dust
in the depot. ;)

Thanks for sharing Knoledge.

Alexandre.
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#10 Richard Andrewski

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Posted 02 July 2007 - 07:14 PM

Great. Now I know what to do with a couple of 1k Mole Fresnels that are collecting dust
in the depot. ;)

Thanks for sharing Knoledge.

Alexandre.


Right! That's the idea. Just follow the safety guidelines in the article on Electrical Safety and all the guidelines for handling and use of the metal halide bulbs. Also, it's not a given, as I mentioned in the article, that the glass in the mole's will stop the UV; part II of the article talks about my research on the subject. In fact, the borosilicate glass in many pro lighting lenses actually allows UV to pass. Believe it or not, cheap window glass is far better for stopping UV transmission than the borosilicate. Tor those reasons please use either a thin glass UV stop filter on the inside behind the original lens (to stand up to the heat) or some of the UV filter gel mentioned here.
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