This is topic Heat issues version 3 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Sam Hunter (Member # 1119) on 09-30-2002, 11:39 PM:
My lamphouse project is basically complete but I am worried I may have a major heat issue with it. I am using an EKD bulb 120V, 650 Watts with a 6" Ellipsoidal reflector. At the second focal point about where the aperture would be the light beam is pretty intense and quite hot. It is hot enough to turn a chrome-plated ruler blue. I really do not want to hook this thing up to my BX80 and burn a hole through it and melt or burn film. Although I would think a 7K lamphouse would heat the aperture up about the same and with the unit running it should cool it down. I just don’t know and need some input. I may back down the lamp wattage about 100 watts or so.
Here are some photos of my setup for reference.
Broke one of the rules on this one.
Brad will push the reject button if I am not careful.------------------
Samual Hunter Sr.
KC5ZSL
Posted by Aaron Sisemore (Member # 145) on 10-01-2002, 01:05 AM:
You may need to get a dichroic filter for the snood of your lamphouse- this will block much of the infrared emission from the lamp, thereby cooling the beam.Additionally, you may not have to have the beam 'pinpointed' at the aperture in order to to get an even illumination. Once again, the IR is less concentrated.
If things are still too hot, water cooling of the gate is the next logical step.
-Aaron
Posted by Jeff Stricker (Member # 224) on 10-01-2002, 07:11 AM:
Sam, I'm running 360W quartz halogen. There's enough heat/light energy at the film plane to start a piece of paper on fire. But with the BX-40 in operation (no filtering) the's no problem with heat. I've got a feeling you will be OK...as a test get a piece of junk film, make a loop and run it round and round and see what happens.
Posted by Sam Hunter (Member # 1119) on 10-01-2002, 09:12 AM:
Hey Jeff,
Just curious, what type bulb are you running and are you using reflectors/lens?
Also, where could I find a dichroic filter ?
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Samual Hunter Sr.
KC5ZSL
Posted by Aaron Sisemore (Member # 145) on 10-01-2002, 11:11 AM:
Most cinema equipment dealers should be able to get glass dichroic heat filters for you. Specify the size and they should be able to get pretty close to what you need.-Aaron
Posted by Jeff Stricker (Member # 224) on 10-01-2002, 12:55 PM:
Sam, it's an ENX (82V 360W). This has a built - in reflector. In front of that I'm using a condenser lens rescued from an old photo enlarger. Distances were adjusted to focus the spot at the film plane.I see you are an amateur radio op. My call is W9GY. 73 Jeff
Posted by John Pytlak (Member # 331) on 10-01-2002, 01:42 PM:
Tungsten-halogen lamps have proportionally more infrared heat energy than xenon arc lamps. If you can fit it into your optical path, an angled dichroic filter that reflects the IR to a heatsink would work well. A heat absorbing glass (like the old Pittsburgh 2043 filter) works well too, but absorbs rather than reflects all the IR energy, so it gets really hot!Don't forget that the film is moving by at 24 frames per second. You need to reach some pretty hefty power levels before you damage movie film.
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
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