It's not unusual for manufacturers to promote their products as "innovative." It is, however, unusual for the products to actually be innovative. But the new Lightlock, developed by the Royal Shakespeare Company (RSC) and manufactured by Total Structures, actually is a very innovative idea with a very practical purpose – it dampens the centrifugal force of rotation produced by moving lights as they pan on flown structures. Rollin' but Not Rocking
You've seen it before; when a moving light on a batten or truss swings from one focus position to another and stops, it oscillates back and forth until the motion dies down. The Lightlock prevents that from happening, even on lightweight hanging structures.
The Lightlock looks like the base of a moving light, only skinnier, with dimensions of 20.3 inches by 16.9 inches by 3 inches high. It weighs 31 pounds and it runs on 80-256V. It attaches to the base of a moving light, and the whole thing attaches to a truss, a pipe or any other flown structure. The Lightlock has a power feed – you can run a single power cable to them. No data feed to the Lightlock is required.
The unit works by accelerating and decelerating a weighted mass in opposition to the swing cycle of the movement. The best way to understand it is to go the Web site (rsclightlock.com) and watch the short video that illustrates it. It shows a mover hanging by two points and swinging from one focus position to another. Everything looks great up until the point where a tech walks over and turns the Lightlock off. Without the device engaged, the beam starts swinging uncontrollably all over the focus target.
It Can't Be
Several people in the lighting industry forwarded the video to me and I could not figure out how this thing could possibly work. Surely the video must have been doctored, I thought. Or maybe they weren't using the device in the same ways I would. So I demanded they ship one to me so I could put it through a variety of tests.
The first thing I did was rig a 4-foot piece of 12-inch box truss with two chain motors from a height of 30 feet. Then I attached a single Martin MAC 3000 fixture to the truss, which is the same fixture they used in the movie. I panned the light approximately 90° and stopped it. The inertia of the moving fixture transferred to the truss after the light had stopped dead in its tracks, and the truss continued to swing back and forth, causing the beam to move for about 20 seconds until it finally stopped. Then I took the Lightlock, rigged it between the truss and the moving light, and I repeated the procedure. The light swung 90 degrees and the truss barely swung. Within two seconds, the light beam and truss had settled on the focus target. It worked just like the movie on the Web site.
Next I took the Lightlock off and rigged the moving light directly to the truss. I then connected the Lightlock directly to the top of the truss using the clamps it came with. I repeated the procedure, panning the light from one position to another, and I got exactly the same results. It didn't matter whether the device was attached to a truss or the fixture. After that, I was really getting curious about the thing.
So I put the fixture into a swaying ballyhoo with the light beam flying all over the studio. After a few seconds I stopped the light. This time it took about 20 seconds for the motion to halt, but it did. The beam slowly crept back to its original focus position. I had fooled the device, or so I thought. But when I tried the same thing with the power to the Lightlock off, I realized it would take a full minute or more to stop the motion of this giant lighting fixture. The Lightlock really does work. (The manufacturer points out that multiple Lightlocks can be stacked on a single structure to greatly increase the dampening effect. -ed.)
Tormenting the Lightlock
But the MAC 3000 weighs a lot, and has a much faster moving pan and tilt than many other moving lights. Let's try this bad boy out with a MAC 2000 or a VL3000 and see what happens, I thought. So I swapped the fixtures and again I tried the ballyhoo procedure with the Lightlock on. When the light stopped moving, it went right back to its focus position in two seconds; it parked right on the money. Damn, I can't break it. This thing works great.
It was time to take her to the next level. I hung a torm rack vertically with three MAC 700 fixtures, one under another, on a firm metal rack. The torm rack was suspended from the truss by spansets only, meaning nothing rigidly connected it to the truss. I panned the lights from one focus position to another at maximum speed. The torm rack swayed heavily to one side but then stopped once the light stopped. The beam did not stop in the exact desired position, but it didn't swing back the other way. The Lightlock worked.
But then I put the three moving lights into a ballyhoo, throwing beams of light in opposite directions for several seconds before suddenly stopping all movement. The torm rack immediately stopped swinging when the lights stopped, and within four seconds the light beams settled back on their desired focus position.
Mind you, this isn't exactly what the Lightlock was designed to do, but the device did quite well in this extreme test. (Again, according to the manufacturer, this situation is better handled by multiple Lightlock units. -ed.)
The only downside is that if you want to use it on a big musical and you expect a bunch of movers to be able to ballyhoo then stop on a dime focused right on a performer, it will not be instantaneous. The lights and the rigged structure will stop rather fast, but not on the exact focus position. It will take another 20 seconds to slowly creep over to the correct focus position.
The bottom line, though, is that this device works precisely in the manner it was intended. You should rig a fixture from two points to make it work; that's physics. If you are in a theatre and want to move a bunch of lights from one position to another and stop the light beam in a desired focus, you can. If you have a pod of lights that will fly in on wires and you want to prevent the pod from swinging once the lights stop, the Lightlock is the device for you.
RSC Lightlock
What It Is: Motion dampening unit for automated lighting
Who It's For: Users of automated lights on flown structures who want to minimize unwanted oscillations due to the torque of movement
Pros: Does exactly what it is intended to do – stops rotational movement very quickly
Cons: Doesn't always allow for precision focus position with a single Lightlock unit
How Much: MSRP: $2,499.
