BUILDING 1-2-3K LIGHTING

This entry was posted on 9/2/2006 11:07 AM and is filed under Pre-Production.

Making a movie with "Home Depot" work lights is fine for heavily diffused lighting but what do you do when you need more powerful fresnel lights like a 1K, 2K or a 3K but don't have that kind of money? You have to get creative and resourceful to turn these kind of problems into solutions.

Making a fresnel lens was out of the question for me because I'm not a glass blower and I don't have the shop to grind the lenses myself. My only option was to focus light using concave reflectors ganged behind several light sources. Determining the bend radius in the reflector metal for optimum reflection focusing was going to require some time consuming experimentation.

One of the big problems with powerful lights is how much it costs to replace the lamp bulb when it eventually blows. That's why I decided to use the same inexpensive 500 watt halogen lamps I was already using in the work lights. I already have inexpensive spares for those on hand.

My Producer Gabriele Andres and I went shopping for the lamp bases for those lamps at Sun Lighting in Tucson. They sure seem to have everything at great prices. We also got very lucky because while I was still designing the box shaped light housing in my head, they offered me this custom reflector that had been a cancelled special order that had been collecting dust for years ever since. The moment I saw it, the light bulb over my head went on and I had the entire design flash before my eyes.

In that moment, the 1-2-3k light was conceived. Yes, I needed a 1K light and a 2K as well as a 3K but with this reflector, I could use the cheap halogen lamps and split the electrical load for 1K, 2K and 3K worth of focused lighting because of the focused nature of the reflector itself. Problem solved.

My new 1-2-3K light design is simple, lightweight (only 5 pounds) that can be easily and inexpensively maintained. It took about 5 hours to build in the backyard using simple hand tools. It throws enough light to light a night street scene - that's exactly what we needed.

The design of the lighting core is an array of six halogen lamps arranged radially around a thin 2" conduit pipe at the focal point of the reflector dish. The wiring is divided into operating either two 500watt lamps (producing 1K of light) and four 500watt lamps (producing 2K of light) or throw both switches for all six 500watt lamps (producing 3K of light, if plugged into a line rated to 30 amps). I can just reach into the lamp array and replace a blown bulb without any tools and the bulbs only cost about $3 a piece, so even if I blow all of them, it costs relatively nothing to maintain.

These three choices of 1K, 2K and 3K light output is why I call my new light the 1-2-3K Light. For about $100 and 5 hours of labor, I don't have to rent them, which is a good thing, considering that I don't have the budget to rent any lighting equipment. Below are the assembly photos.

 
First, I drilled two sets of holes through the inner and outer structural tubes of thin steel conduit.
Then I drilled and mounted three angle irons that I would use to mount the reflector..
I used two long screws to suspend the inner tube within the outer tube to thermally insulate the outer housing.
This is what the housing looked like after assembling the two tubes together.
Then I bolted the reflector onto the housing.
Using the angle irons as a drilling template.
There is all of the metal fastened together.
Then I began fabricating the wire harnesses..
This is a complete circuit for the 1K (2 lamp) harness.
This is a complete circuit for the 2K (4 lamp) harness.
This is a clear photo showing the radial array idea. Notice how thermal energy transferred to the inner tube is isolated within the outer tube.
After attaching the six lamp recepticles into the array, I attached the two harnesses into the power line using caps and electrical tape.
I wired both switches into both white lines and wired both black lines directly to the lamps.
Wiring the bulbs in parallel instead of series means even if I blow a bulb, the others won't go out.
I drilled holes to mount the toggle switches and feed the power line through to keep it sleek and simple..
This is what the lamp array looks like complete. Notice the ring over the tube that creates a gap for the wiring.
The lamp array is perfectly positioned for maximum light emission at the focal point of the reflector.
This is the array. Notice how much clearance there is for changing out the tubular halogen bulbs.
Installing the bulbs is easy, just don't touch the glass with bare skin so the bulbs don't instantly pop.
Here, all of the bulbs are installed into the array. Notice how each bulb directly faces the reflector.
This is a detailed view of the array assembly.
It may be crude and simple but it works.
The whole thing only weighs five pounds and can be mounted to just about anything.
You can't make it out well in this contrasty flash photo but it easily lights up the houses down the street.
 

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