GE MQI 250w MH and UV stops...

[Quin]

Hi folks,

Just a quick question or two for you. I recently bought an Eiko 250w double ended metal halide lamp for use in my projector build. I've since found it to be unshielded to UV rays and - seeing as I don't have a UV stop of any type - figured it'd be unsafe to use.

I've now sought advice from the local electrical shop and bought a GE MQI/250/T8/43 . The suppliers assure me it is UV shielded, however everything I read demands the lamp to be used within an enclosure with adequte UV shielding.

My question is this: do the lamps with UV stops still recommend using in a UV shielded enclosure? Am I getting overly concerned about the warnings on the box?

Finally - Can anybody direct me towards a company (preferably UK based) that can provide me with a UV stop of some description, encase I cannot resolve the issue at the lamp level.

Apologies if any part of this has been asked before, I couldn't find the answers. Many thanks.

[ELiTeHaYDeN]

Need not worry about UV me thinks simply because the LCD consumes so much light, and UVC(most dangerous) will not penertrate Glass(eg, wont get past your projection lens) however, UVB and UVA will with only minimal deductions(penertrate glass that is..) - but providing your cabinet has no light leakage then this shouldnt be an issue either due to how much light the LCD absorbs(or fails to pass for lack of a better term) ... somewhere in the vicinity of 10% at BEST out the projection lens, then once it hits the screen only minimal amounts once agian are actaully reflected(depending on screen gain) .. so in short, yah I dont really think its a issue, but seeing as UV filters are so cheap, your silly not to try and protect yourself and your family, you only get one set of eyes.

I'd say one of the best/cheapest options is standard glass$(5NZ)with the automotive type clear UV filter$(5NZ) (similer to tint film) applied. - bout $7 US in totel.

Im not too sure if UVA - C - B can actaully penertrate wood etc..but im pretty damn sure it can.. it would probebly be better to be safe than sorry and put some sort of metal enclosure around the bulb, or sheets of sheet metal on the inside of your projector.

[edit] to answer your other question, I had a 400w Syvlania Bulb, that had a huge UV stop envolope, and it actaully said on the packaging, UV stop envolope, and it still suggested that a UV Stop be used(they suggested a standard difuser, like used in flourencents.. the plastic cover is the diffuser i believe. [/edit]

[Steamer]

Guys,

The most important thing to protect (aside from your eyes) is your most expensive component--that being the LCD panel. UV rays are an LCD KILLER! it will turn black in a relatively short time. The UV envelop on the lamp should be sufficient but you don't want to "not worry" about it getting absorbed by the LCD panel. The cheapest way is to use XL10 lexan/plexiglass from your local home improvment store and place it in the light path twix the light engine and the LCD panel. Alternatively, the regular glass outfitted with the clear UV protectant from an autoshop is a good idea.

Steamer

[justme]

Hey is there an easy way to tell this from any other clear plastic sheet? I know it's coated on one side, can you see a difference? Unfortunately where I live corruption is the rule not the exception. I'd hate to not only get ripped off but ruin an lcd too.

[Steamer]

XL10 can be found at your local Home Depot, or Lowes. You should be able to ask a floor staffperson to direct you to the XL10 and it should be labeled or something. Of course, this is merely conjecture, as I have yet to go thru this process myself. I will try to go and obtain a piece tomorrow and hopefully I can be better informed. You, in turn, will become better informed as a result.

Steamer

[ELiTeHaYDeN]

Originally posted by justme
Hey is there an easy way to tell this from any other clear plastic sheet? I know it's coated on one side, can you see a difference? Unfortunately where I live corruption is the rule not the exception. I'd hate to not only get ripped off but ruin an lcd too.

Welcome to america he says.... perhaps that was a tad harsh.

if thats the case, best idea for sure, is get a standard peice of thin glass and put the UV film on it, both sides if you wished.

[TaskMaster]

Originally posted by ELiTeHaYDeN
Welcome to america he says.... perhaps that was a tad harsh.

That's OK, we don't mind... people always take pot shots at you when you are #1!

The Lexan is clearly marked on the film protecting the coated side so you cannot mistake it.

[ace3000_1]

Welcome to america he says.... perhaps that was a tad harsh.

That's OK, we don't mind... people always take pot shots at you when you are #1!

Aslong as thats all taken as a joke...........

Guys to be quite honest if your bulb has a UV stop you dont need the lexan. The UV stop thats built into the bulb blocks 70% and up of the UV, the frensels also block UV. A condenser (unless its upto UV spec) will also block UV light.

Unless you are using the 100% of the light from your source (which imo is practically impossible in our setups), you will never have that 30% of UV hit your lcd. All lexan will basically do is cost you light and its advisable to get a PROPER UV filter to filter the UV light from an UNPROTECTED bulb.

The reason UV block came about in bulbs is because of food and human saftey in shopping malls. Bulbs that are unprotected will discolour food and give people a tan. I have never ever gotten a tan from my 250w HQI-TSD UV protected bulb yet, and beleive me ive spent hrs infront of it. A human being will tan before an lcd, so will food.

Trev

[justme]

Well that was interesting. I was actually just talking about the city and surrounding area not the whole country. I was just a bit irritated after dealing with some of the local busineses here.

Let me explain what I'm doing. Since this will be my first pj I'm going to use a 5.6" TV type low res (regardless of what they claim) LCD and the lamp & condensor from an old slide projector. The only new stuff will be the triplet and some fresnels from an office supply store. The plan is to build this one, likely into an old pc case, play with it for a while and then with what skills learned build a higher resolution, brighter and better planned pj. This way if I screw up the LCD it only a cheap one and not something I paid $200+ for. I would still like to be able to reassemble the little monitor and use it for something else so the cost of a small piece of glass or plexiglass is worth it. The lamp for this project is only powerful enough to be able to be used if the room is dark so the less light lost the better. The XL10 being clearly marked is the main info I was lookin for.

thanks

[ace3000_1]

If your going to be using a halogen make sure you use a UV filter or your lcd will go black forsure. Use a IR filter aswell.

Trev