HMI from China via Ebay

Hi Guys,

The back story
I am a poor indie film-maker who, I would guess like a lot of others, really wanted a small 575 HMI Fresnel of my own just for doing small indoor shoots, as a main key light as my florescent light banks are great for fill but just too soft as a key light. There was no way I could afford an Arri and i tried to buy second hand but they are hard to find. So I was tempted by what looked like a solution in a Chinese HMI via Ebay.

I got it a few weeks ago, but it was poorly packed, bits were broken and scratched etc when I opened it and when I tested it, nothing. The guys in China were actually good about that and sent me some replacement parts and once I got those I changed them over and I also found that inside the ballast that a connector was loose and I got it working.

However on getting it working I was extremely disappointed to say the least. I am got a lighting guru, I am very much still learning but I was expecting a hard flat even, flicker free light, the unit is poorly made but I was not expecting so much light to come out of the sides, top and bottom of the unit or for the glass lens not to fit.

I am letting it run, burning it in, at the moment but what I have fight now flickers like hell to the human eye, is not very powerful at all, has two highlight points inside the circle of light it projects and the colour is red in some parts of the circle and blue in others, it gives a double shadow, not a single shadow as I expected. Basically its unusable, is that likely to change if I leave the lamp burning in for more than 2 hours ?

Not only that but while I was testing it/setting it up, my arm was quite close to the bottom of the light, which had some light spill, bounced of metal internal walls and comes out of what I guess are cooling vents ie about 6 inches away and it felt very hot, like a burning and is still a bit sore after more than an hour. And my eyes are hurting. Could this be down to the light escaping from the unit, not through the lens ? It is reflected light but is that still high in UV ? My eyes also seem to ache a bit, are mildly strange.

If I add silver baking foil inside the unit to cut down the light escaping is that dangerous ? Is the quality of the light out put, which to me seems like it must be unusable, normal for a small HIM 575 ?
 
HMI lights generate ultra-violet light, which - like sunlight - can damage your retinas and severely burn skin. HMIs should have a UV safety glass cover to protect people in front of the light, but given the build quality you've described so far I wouldn't be surprised if they'd skimped out on that too. I love cheap film gear as much as the next guy, but I think I value my eyes over my wallet. Either get it looked over by a professional, or bin it.
 
Does any one know about burn in times for HMI lamps, actually have experience ?

After 3 hours the flicker has gone on all but the highest settings on the dimmer. Would that go as well after the lamp has been on for a longer time ?

Rosco makes UV filters, are these rolls, will they be able to handle the heat if they are over the barn doors, and so if I use that it should deal with any UV from the front of the lamp ?

If any one has ever made their own HMI or adapted one, I have wondered about the idea of trying to get a new housing, ie an old HMI that is broken or maybe a new blonde or something and re fitting it?

It cost about $1300 I can't afford to just throw it away!
 
Holy moley, is it radioactive too? :eek:

I've never operated a brand-new HMI, so I don't know about needing to let it "burn in".


If I add silver baking foil inside the unit to cut down the light escaping is that dangerous ?

Yes, that is dangerous. You'll likely be blocking air circulation, which will cause several overheating issues.

How much was it, btw? Just curious.
 
Flickering is the sign of a bad ballast. I had the same issue with a home-built video projector several years back.. skimped and bought the cheapest ballast I could find and I paid for it with a picture I could only look at for about 5 minutes before getting a severe headache.

My suggestion is to send it back and demand a refund, then buy yourself something that is known to work well.. there's nothing wrong with used lights. I've got about 10k worth of fresnels in the garage just waiting for my next shoot. :)

For used lighting, it's hard to beat the prices at Pyramid: http://www.pyramid-films.com/ they often has stuff listed on ebay too.
 
Good answers here.

The only thing I'd add is too stress that you NOT add any sort of material to the inside of the housing to cover up the venting. Overheated HMI's are very dangerous.
 
hi mavboy,

if you are worried enough about the light to post here i would think there is something wrong with it.

uv from the lamp can be very dangerous. it should have a micro switch on the front door to cut out the lamp if it is opened if it doesnt it surely does not meet specs.

do not put anything inside it ...especially something that will conduct electricity to the housing.

from what i have seen of these chinese lights manufacturers they have a severe lack of knowlege of what the earth is for.

i have seen several of their red head copies that have no earth contact at all.

i am afraid it is a case of you get what you pay for.

i would send it back and demand a refund.

cheers
ian
 
hi david,

freaking scarey is right.

i have rewired several of these ebay lights for other people

i could not get them to pass a simple electrical safety check.

when i investigated, the earth line ran to the switch and stopped there.

bear in mind these are metal lights unlike the originals which are fibreglass and if they go live , the current will travel to the stand and ruin your whole day.

also rcd safety devices depend on a flow to the earth to trip out

without an earth they wont trip until you touch the stand and create an earth...... by then it could be to late.

i would strongly suggest anybody buying cheap lights to get them tested and tagged by an electrician.

cheers
ian
 
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