I have seen these lamps being sold at Autoshops. Are they alright to use for a PJ. Do the globes need to be changed to a different type or the ones they are fitted with are fine. I know these babys put out a lot of heat. I just want to know what sort of results are people are getting from using these types of lamps and what changes are being made to them to get the results.
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Tell you the truth, I was using one until I got an OHP bulb and tried it
out against each other. The 400w OHP bulb killed the 500w work
light. I think it's the reflector... it spreads out the light too much.

Maybe if you put in a baffle(?) so that only a tight beam got out it
would work better. I didn't have the patience.

- edit -

I also think the actual arc of the light is bigger, too... which makes the
system suffer somehow.

So basically, if I take the bulb and connectors out of the frame, set it up with some sort bowl like reflector behind it (I think someone on this forum made one from a stainless steel mixing bowl from Ikea) and I should get a plesant result? The only reason I am asking is because buying these types of 500W lamps in Australia are extremely cheap. AutoShops will sell a pair for a total AU$25 when on sale. I have been trying to find some pics of some succesful results of these lamps on this forum, so if you know of some,please point the way. I have had success with placing a 15" LCD on a projector, which I later cased in MDF. I made it 4 years ago and it is still going strong today. I am now looking at making one with with a Hami 8 inch. My first projector cost me $0, so being in the nature of being such a tight @#$%, i am looking at these lamps for a alternate light source, I will spend the extra$$$$ (God Help Me) if these lamps are no good for this type of project.............

Halogen lights like that are not very good, but are usable.
The Pros:
1. They're cheap
2. They're readily available

The Cons:
1. They get very hot
2. They are not as bright
3. Their color temp is too yellow
4. The arc is very long

Pretty much the only reason to use them is because they're cheap. But using a cheap hot lamp will make you spend more on cooling, and may cause parts to be damaged (LCD, fresnels) which will have to be replaced. Going frugal here might mean you'll have to spend more later.

You're seriously wasting your time with a long filament halogen lamp like that. Results are poor enough from short filament OHP lamps. A floodlight like that would be abysmal.

I have asked this before, but this is a good time to ask again.

The "point light" is only important if you have a rear fresnel. Right?
In other words, if you were able to flood the back of the LCD with bright even light, then you would only need the front fresnel to focus the light to the triplet.

Do I understand that correctly?

The argument that halogens are really hot may have some debatable points. They are hot but, compared to Metal halides are they hotter? It seems that most of the metal halide PJs have quite a few fans in them to keep the lcd cool. Most OHPs with Halogen bulbs have a max stage temp. of 100 - 115 degrees with usually one fan in them. I can't accept the argument of "halogens are really hot".

The OHP lamps are fine for our PJ they have a dichotic reflector that lowers the heat and it also increases the color temp. They don't last long but can be had for less than $10.00 most of the time. Most run on 82v so you will nee a diode pack from an OHP.

The standard 2800k shop light lamps are too yellow and have an 60mm to 80mm filament.

I've always found that to be a wonder, as well. Most of the really high
wattage lights I've ever encountered are "really hot"... and yes, the OHP
that I ripped the light out of just had 1 fan.

I seem to be getting great results considering I'm just using a 360w bulb,
albeit slightly dim. But in a dark room (which is really what I would think
I would watch a BIG screen in) it works great. I still want to get a lux
meter and see exactly how bad the bulb does.

I've also been toying with the idea of using a 500w halogen bulb and bulb
holder from a work light with one of the reflectors out of the OHP I got, but
when I looked up the bulb, it seems that even the 500w has only around
10000 lumens. Not good, especially if the arc length is a problem. It looks
like it would be HUGE.

But I agree with PLJack... I've seen a decent amount of small projectors
with flood lighting pointing at the back with pretty good results.

12 of one, half dozen of the other. Lumens and color temp seem to be key
for most people. If you like it, you should use it. If you have the money &
time to do a "better" setup, what would you be happiest with?

Seems simple to me.

- edit -

However, when I looked up my bulb again, it does have a rated hours of
~2000... so at least you'd be using a bulb that should last for some time.

Your forgeting the reflector system the OHP lamps have a great reflector that will make a lot mort light than a condenser system that you would have to use if you make your owin.

True... I figure they probably spent a fair amount of time engineering the
OHP to work well with what it had. They had a set problem: use cheaper
bulbs, and so they really did well with those reflectors, I'm sure.