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Cheap HMI's


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#1 Robert Hughes

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Posted 06 September 2007 - 10:31 AM

I was looking at that auction site yesterday, saw somebody in Photography>Lighting>Continuous Lighting selling HMI units, new, for $350. These use the kind of HMI bulbs you see in gas stations and parking lots.

Anybody have experience shooting under these kind of lights? Are they usable, cheap equivalents of the real thing, which start at $1500?
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#2 John Holland

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Posted 06 September 2007 - 11:45 AM

Dont know about over there but hmi's bulbs not used here any petrol stations or car parks you sure they are hmi ?
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#3 robert duke

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Posted 06 September 2007 - 03:11 PM

Dont know about over there but hmi's bulbs not used here any petrol stations or car parks you sure they are hmi ?


First these are NOT HMI these are HID. They have a average color temp of 5200 k. They are workable but the ballast is delicate. I bought one to try it out and see. It is very sensitive to power range. I had a very hard time with getting the light to strike on certain power circuits. I them had a ballast fry. Since these are just HID lamps and ballasts, I have been looking for a comparable ballast via electric supply houses. I wouldn't recommend them. reliablity is just not worth the $.
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#4 Matthew Buick

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Posted 06 September 2007 - 03:38 PM

Dont know about over there but hmi's bulbs not used here any petrol stations or car parks you sure they are hmi ?


There are some in my local Cathedral. I don't think the light looks very nice, slightly cold, and a bit too blue.
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#5 Chris Schlaghecke

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Posted 12 September 2007 - 08:44 PM

First these are NOT HMI these are HID. They have a average color temp of 5200 k. They are workable but the ballast is delicate. I bought one to try it out and see. It is very sensitive to power range. I had a very hard time with getting the light to strike on certain power circuits. I them had a ballast fry. Since these are just HID lamps and ballasts, I have been looking for a comparable ballast via electric supply houses. I wouldn't recommend them. reliablity is just not worth the $.

I agree Robert, but its not just the reliability, its also the color spectrum produce by the various types of commercial HID lamps. Some of them have a huge green spike whilst others end up quite magenta.
I was lighting for a TV show covering an international rugby test, and even the lamps lighting the field had huge green spectrums. My only way out of it was to use 1/4 green on my lamps to correct the talent in the shot to closer to the background color, then CCU had some chance of getting a balanced image.
Sometimes the cheaper lamp types can end up causing you more headaches than if you just used to proper source in the first place.
Chris
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#6 Richard Andrewski

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Posted 16 September 2007 - 05:29 AM

There really is a lot of confusion about the different kinds of metal halide bulbs and HID families.

Actually calling any fixture an "HMI" is technically incorrect. HMI is a just a bulb and is a trademark of Osram Corporation. It is not a fixture even though everyone refers to the fixtures as "HMIs"; they would be more technically correct in calling them an HID fixture as even HMI belongs to the metal halide or HID family--as does sodium and mercury vapor too. The bulb used in the unit in question is a cheaper consumer technology than HMI but is basically the same type idea. As is the ballast too. In fact there are not all that many differences between the technology of the ballasts across the HID families. You can think of the difference as one being for "consumer" or commercial use and the other mostly designed for "entertainment" or film/tv/professional use.

You can find a regular consumer high grade metal halide bulb from companies like Ushio (primarily meant for aquarium and grow light use) that is a high CRI of 90 and has very good color rendering but has a mogul base and is rather large so not so desirable for the kind of fixtures we like to use. You can also find terrible grade bulbs from the same company too which are more at home in street and warehouse lighting. The main difference is the quality of the materials used inside the bulb. Another consideration is the environment that the bulbs are designed to work in and also the base used which is typically an Edison or Mogul base on the cheaper consumer versions and a more professional G22 or G38 on most of the HMI type family--what we're used to using classically in stage lighting fixtures.

Another major difference though between HMI type family and the others is hot restrike capability which the "consumer" versions don't have. A common mistake made about Osram HMI bulbs is that people think they are 5600K. Not true. They are actually 6000K and CRI is median of 85 which is not even as high as the mogul base Ushio Aquarium bulb I spoke of earlier.
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