Home depot has MH and MV bulbs and ballasts...

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Ok, I went down to Home Depot today, and found that they have 400watt and 175watt metal hallide bulbs (damn those things are huge!!!!) and also 175watt mercury vapor I think.

Now - the mh bulbs cost around $40. But the cheapest light fixture (not seperate ballast, they only have them built into fixtures...) was $108, and it was huge!

The mercury vapor bulb had a fixture for it too - only around $30-40, with 24,000 hour, 7,900 lumen bulb!

CAN it be used? It looked like the arc was huge (didnt get to turn it on). It was around an inch in lenght? Will it be ok to use still? Im thinking - 15" lcd, that bulb, fresnels from us (maybe the standard triplet, maybe Ill try the 135mm lens that I have) and project onto a 84" 1.8 gain screen. Will I get a fairly bright image in a dark room?

P.S. Hmm the MH and the MV looked similar to the MH and the High pressure sodium (maybe thats what it was at home depot...heh) that are here:

http://www.ushio.com/categ_general.htm


Thanks for any tips,,
Cheers,
Alex
 
Right in front of you - 7900 lumens. Not nearly enough for most people. 400w metal halides put out around 40,000 lumens, and the resulting brightness is comparable to consumer home theater projectors (LL had a guy measure 600 lumens a few days ago, likely less than that if he'd measured ANSI lumens).

The arc size determines how hard it is to focus an image, and if it's too large, you'll get enough divergence to cause FOV problems at the triplet (resulting in dark corners). I'll make an edumacated guess based on raytrace and say anything above maybe 1.5-2" is totally unusable because of FOV issues. The preferred 400w MH bulbs have a 1" arc, and many have used them with success. Oh, and also, reflector size / arc size is proportional to the efficiency of your reflector, it exaggerates non point sources.
 
Squash,
Thank you for an informative reply. The arc is around 1", so it should be ok, so it seems that the light output is not as great as an MH would give. Thats all the problems? I think its still better than a halogen (my 500watt halogen gives out about 8400 lumens I think, gives more heat than light probably😀 )

Thanks,
Cheers,
Alex
 
They all put out more heat than light - a straight wattage to luminous energy conversion gives I think 600 something lumens. You don't see the huge regions in the spectrum emission charts because they leave out most of the IR band(which dwarfs the visible band in size), where heat transmission occurs.

Normal arc metal halides typically put out around 80-110 lumens per watt, halogens put out around 15-25.
 
And btw, you can pick up a 400w magnetic ballast for $50 or so if you look hard enough (disclaimer, does not include shipping). Lumenlab sells an electronic ballast for $100.

The two best lamps at 400w would probably be the OSRAM HQI-TS 400w double-ended lamps, or the USHIO UHI-S400DD T15 sized lamps.

Each has a certain ANSI type ballast that it needs, so make sure you can get the right one.
 
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