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Author Topic: Calculating stage lighting needs Adam Martin I'm not even gonna point out the irony. Posts: 3686 From: Dallas, TX Registered: Nov 2000 posted 10-18-2002 12:25 AM                     I'm in the process of re-doing our preshow and presentation lighting and I will need to purchase some stage lighting soon. What I need to know is how to calculate the size of the fixtures. If I want to shoot a 72-inch diameter circle of light 35-40 feet, what size ellipsoidal should I use? Is there a mathematical calculation based on lens diameter, focal length and throw distance? And then, is there a conversion for angular measure (ie, does a 6x18 put out a 10-degree cone)? I should have paid attention in math class.  |  IP: Logged Paul Mayer Oh get out of it Melvin, before it pulls you under! Posts: 3836 From: Albuquerque, NM Registered: Feb 2000 posted 10-18-2002 01:27 AM                        A 6x22 has an 11 deg. spread and will give you a 8' spot at a 40' throw. One can also get these instruments fitted with an iris in the gobo slot to allow narrower beam widths. A chart from the nice folks at Altman Lighting:here Ja ne, Paul  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 10-18-2002 11:44 AM                        Yeah, we all should have paid more attention. This should help: go to http://www.altmanltg.com/ Under "Product Index" - "Ellipsoidals" are the photometrics for Epical Altman instruments. ETC Source 4 info is at www.etcconnect.com Good luck. Frank  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 10-18-2002 11:46 AM                        woops, sorry, didn't see Paul's post. That's the place.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 10-18-2002 12:06 PM                     Check out the source4 fixtures with the precision glass reflectors they do the best job and if only a few are required they would fit a budget as they are pricy THey also have an option of an onboard DMX controled dimmer  |  IP: Logged

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