???

It will keep your parts from aging to fast while using the MH bulbs. They put off a lot of UV light.

You're going to get a lot of different answers on this one

I had my projector running for over a year with no UV protection and everything stayed just the same as when I first installed it.

My personal thoughts on the matter is that the Ushio bulbs outer glass layer helps reduce UV enough. But depending on the lamp used, well maybe UV protection is needed. In any case it won't hurt to have some UV protection in there, well other than 10% less lumens

I second jonjandran's comments.

Critical? No. Useful? Possibly. Detrimental? Not too much.

Going to try to refrain from starting a "big thing" here... If you're going to buy a UV filter, you may want to look into a UV and IR filter, known as a "hot mirror". They're smaller, better, and more expensive (~$60 or so). But, if you buy one as a fix all solution it's only like 2 times as much money...

I chose to put a UV filter in my projector.

It is possible that the existing protection on the LCD will allow it to last in the high UV environment that the lamp puts out.

However, it's guaranteed that other plastic items exposed to the lamp WILL degrade over time. 1 year isn't really long-term in my books. Any plastic (ie: LCD frame) exposed to the lamp will degrade and become brittle. It may take a couple of years, but it absolutely will happen. The LCD will PROBABLY egrade as well,

In addition, while you are tweaking your projector, you should take precautions. There is more than enough UV in the output of many MH lamps to make you sick with only a few hours' exposure. Since I'm always messing around inside my projector, I consider it to be a reasonable safety precaution.

Decide for yourself, but the safe money is on having the filter.

I dont' want to steal the thread or anything, but I was wondering if anyone knows about any UV emission from the 575watt HMI bulbs?

I can say this. With the UV lexan installed, I can hold my remote in font of the triplet for a long time and the buttons barely glow. Without the lexan, when I do the same thing they get bright fairly fast.

I figure with all the light reflecting off the screen, if UV is in it it will be reflecting also. Another thought, the UV might degrade your BO cloth.

I use the UV lexan, it is temping to take it out for the extra brightness though.

EDIT: this was with the LL65K and Ushio S400DD lamps

Hmmm... intresting! I've tried to find a DIY UV test. The 2 things I've come up with are a little card with "A" and "B" printed on it (for type A and type B UV presumably). If I take it outside... um? I forget what happens exactly; but one way or another the card indicates that both types are coming into contact with the card. Since the card came with a UV filter lens for a camera, it's possible the card is misleading, or maybe tuned to what the lens can block. The other test I have are some "UV Beads". Outside they turn yellow or purple (maybe 2 different kinds of UV? Maybe just 2 pretty colors? Dunno...).
Both of my DIY tests do the same thing as outside with light directly from the bulb, after the light passes through my LCD they don't change at all, or not perceivably to me.

As for the 575 HMI: I got a straight up sunburn from my bulb. I probably "played" with it for about 2 hours max. Now when I mess with it I wear long sleeves, a welding mask, and towels to cover my neck...

And in about the same amount of time, I flash burned my eyes pretty badly. They were literally sore and irritated for about a week. Scared me into wearing sunglasses while I worked. I've heard the cheap Chinese knockoffs have little to no UV blocking at all. Not sure about the Osrams.

Thanks but I decided not to put UV filter because I didn't find a place that I can buy it...
But it isn't matter because I FINISH FINALLY MY PJ! So soon I will send some pictures.