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Posted by Miran Starman (Member # 1191) on 09-02-2002, 04:50 AM:
Did someone could help me with information how to calculate correct wattage for xenon projection lamp according different conditions like: cold - hot mirrors, hot filter, two - three blade shutter, different optics, glass of projection port window, size of screen, gain of screen etc...
Posted by Leo Enticknap (Member # 534) on 09-02-2002, 06:46 AM:
I don't know if there is a formula which exists to balance those variables, but the bottom line is that you need (according to the SMPTE specs) a big enough lamp to light the screen evenly to 16 foot-lamberts.If, running at maximum current (amps) in the manufacturer's recommended operating range, the screen brightness is less that that, you need a bigger lamp (and possibly a bigger rectifier). If it's significantly over, decrease the current. If you need to decrease the current below the minimum current in the operating range, install a smaller lamp.
Posted by John Anastasio (Member # 607) on 09-02-2002, 08:26 AM:
Assuming a shutter efficiency of 50% (two-bladed), I think 5 watts per square foot of screen size should give you a good approximation.
Posted by Gordon McLeod (Member # 33) on 09-02-2002, 09:43 AM:
There are far too many variables mirror type heat filtering lens efficiency screen gain and aspect ratio
I usually take the manufacturers specs and almost double that requirment as there are based on brand new everyitem not 3 years down the road
Posted by Gerard S. Cohen (Member # 994) on 09-02-2002, 12:22 PM:
Welcome Aboard, Miran!
The closest I got to Slovenia was running Meopta projectors. (I liked the micrometer/microscope feature that enabled the precision adjustment of the exciter beam through the sound track.)
Good luck,
Gerard
Posted by John Wilson (Member # 269) on 09-02-2002, 08:07 PM:
Question...With the 5watts per square foot guide, will that actually get you to 16fl or take you over into a safety area? Or will it JUST get you there?