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Author Topic: Xenon lamp alignment Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 09-15-2006 01:43 AM                     For a parabolic mirror, all rays of light emitting from the focus reflect off the parabola and travel parallel to each other. Since this is true, if one were to shine a laser pointer into the mirror at a perfect angle such that the vertical angle would not vary up or down and the horizontal angle would not be off to the left or right, one could shine the laser pointer into the reflector at any part of any surface and the light from the laser would bounce to the focus point of the parabola. If one were to mount a thin protrusion centered in the parabolic reflectors rear hole whereby the protrusion would extend into the reflector a sufficient distance, one might see the light from the laser at the focal point. One could then reasonably estimate where the arc of the bulb should be with respect to the reflector. This is just a theory of mine. Does anyone agree or disagree with this idea? Or maybe flying to the moon might be easier  |  IP: Logged Greg Mueller Phenomenal Film Handler Posts: 1687 From: Port Gamble, WA Registered: Jun 99 posted 09-15-2006 12:27 PM                        Here's how I recommend it be done http://www.muellersatomics.com/alignotron.htm  |  IP: Logged Charles Greenlee Jedi Master Film Handler Posts: 801 From: Savannah, Ga, U.S. Registered: Jun 2006 posted 09-16-2006 12:18 AM                        Wonderful tool, not that I should ever have to use one as a lowly projectionist., but if/when I get up to sound tech. something like that may come in quite handy.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 09-19-2006 10:20 AM                        It sure would be nice if the pedestals themselves would have alignment adjustments so they can correctly (and EASILY) align the lamphouse dead-center with respect to the trap. You can futz around with mirror all you want, but if the lamphouse isn't sitting true center, then all you will be doing is trying to correct for that initial misalignment. Seems to me something as so primally important as the lamphouse position as it sits on the pedestal should have adjusting rods so that they can be as easily manuvered as the adjustments on the mirror. I guess this is less of an issue when dealing with an integrated console, eh?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-19-2006 11:22 AM                     Frank, Good pedestals DO have proper lamphouse adjustments. In fact, I'll get a lamphouse on a pedestal aligned far better than a console to projector any day. Most consoles suck in this manner. Examples of pedestals that have lamp table adjustments include Century and Ballantyne (still available...called the 2500B). Simplex only offered limited adjustment on theirs and I don't like using them as a result. Steve  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 09-19-2006 07:59 PM                        quote: Eric Robinson For a parabolic mirror, all rays of light emitting from the focus reflect off the parabola and travel parallel to each other. A parabolic mirror would normally be used for a spotlight. Most lamphouses for projection use a mirror with an eliptical curvature, with one focal point being the arc plasma, and the other just beyond the film aperture.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 09-20-2006 10:36 AM                        quote: Steve Guttag Simplex only offered limited adjustment on theirs and I don't like using them as a result. Aha! Guess which ones I have in EVERY house I work in?!  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-20-2006 05:09 PM                     You can shift the lamp table on a Simplex latterally. Vertically you can use washers to space the lamp table up but that definately isn't as nice as a proper lamphouse table. With Ballantyne pedestals, I grind down the Grade-5 markings (three ridges in triangular formation) of the lamp leveling bolts so the tops are smooth. Otherwise, the lamp table does the schimmy as you adjust the leveling bolts.  |  IP: Logged

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