i will be using a fxl halogen bulb for my projector because i cant afford a mh at this time i was going to use a cold mirror and a piece of ir glass to stop the ir heat in the beam from the halogen
do you think the cold mirror is overkill could i just use the ir glass?

also am i right when i say a 400 watt halogen and a 400 watt mh put out the same amount of heat
i understand the mh puts out more lumens per watt but 400 watts is 400 watts.

Close enough. 335 heat watts to about 380 heat watts.
Both will put out nearly the same heat but the halogen will be about 3 times dimmer. Its also a very warm light that will give you very questionable colour rendering. I'd save the pennies for the MH system or at least leave room for the upgrade.

Cheers,
Kirk

If your shooting through the filter you want a "Hot" mirror. this will strip out the heat (reflect it) and leave you with only visible light. Probably good on any installation but halogen contains higher IR so it might be a requirement to protect the LCD.

Kirk

If at all possible, spring for the MH, halogen puts out much, much lower light levels as well as much worse color index.

The halogen does put out appreciably (though not major amounts) more heat than a MH, but the issue is that you need an MH with around four times as much wattage to get the same light level.

Also, halogens aren't exactly long-life.