Newbie Lighting concerns

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scanboy

Member
2005-08-03 11:46 pm
Hi, I just started to gether part for my first DIY pj. Before I start making orders, I have a few questions.

1. I saw on the LL site that they have this UV filter, is this alone good enough to filter out most of the heat genearted by the light source?
(I plan to do a direct light source without any mirrors with a 400W MH right behind the lcd) And where should I place it? between the light source and the Fresnel?

2. Is the len kit from LL good enough ? do I need another Fresnel between the LCD and the lens triplet?

3. I plan on using the ushio S400DD, is this a good lamp for pj? what about those ED28 (much cheaper), how do they compare with the ushio S400DD? how much difference?

4. I am all confuse about the ballast. Sometimes I see ANSI ##, sometimes M##, which one should I look at when I look for matching ballast for the bulb that I decided on?

5. Will having just one fan blowing out too hot for the lcd (based on my plan in 1.?

Thanks in advance.
 
lots of questions!

1. UV filters remove UltraViolet light (which would damage your fresnels and LCD), not InfraRed (which conveys heat). You need BOTH filters between the light source and the first fresnel. DIYProjectorcompany has some IR filter glass that would work & is pretty cheap. Lexan XL10 also makes a fine UV filter. (Window glass section of Home Depot.)

2. The full lens kit from LL is fine: You get two fresnels and a triplet. Put the 220 mm fl fresnel 220 mm from the lamp arc & 20 mm before the LCD. Try the 330 right against the 220 (on the LCD side) or 20 mm after the LCD.

3. ushio S400DD is a great lamp. But it is the largest you should try. Arc length is the critical dimension. A lamp with a bigger arc length is a waste, since a lot of the light does not make it through the triplet.

4. The ushio is a retrofit lamp, which means it works with an S51 400 Watt High Pressure Sodium ballast kit. Available from many sources. (ie. goodmart.com)

5. I use one 65 CFM fan in my PJ, and it runs very cool. But I pull the air flow over & under the LCD and fresnels, then past the lamp, and finally it gets pushed out of the box. I also use a good IR filter to keep heat away from the fresnels & LCD. If you design the airflow right, then one fan is ok.
 
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