Without a boom arm, photographers affix lights—whether it’s strobes or continuous light sources—directly to the tops of light stands by way of a “baby” spud—the 5/8” cylindrical steel shank that protrudes vertically from the top of a stand and which the majority of photographic lights are built to accommodate. There’s absolutely nothing wrong with this simple, straightforward approach. But know that it can be slightly modified to become a more versatile, easily adjustable light stand. That modification is done with a boom.
A boom, like the Avenger D600 mini-boom arm, is a telescoping metal tube, much like the center shaft of a typical light stand but built to mount and extend horizontally across the baby spud on top of a stand. The boom arm is then adjustable by length, angle of elevation, horizontal position and lateral rotation of the boom itself, which effectively tilts the light source up and down.
You see, with a light source on a boom arm, the light can be easily raised and lowered, moved closer to or farther from a subject, easily angled to or from the subject, and generally moved quickly and easily into a variety of positions, all without having to relocate the stand. A boom arm essentially makes it easier to position light sources exactly where you want them.
More than just making repositioning easy, booms also let you get your light source into positions that might otherwise be impossible. For instance, if you’d like a light over a subject, you can use a stand to raise the light above the frame, and then let the boom arm take the source out and over the scene. It’s invaluable when used like this for everything from hair lights in portrait sets to background spots, as well as for positioning lights directly over tabletop product and still-life sets. The boom allows the photographer to get the light into positions they may not otherwise be able to, thanks simply to the reach of the extended boom.
When working with a boom, be sure to consider safety first, followed by convenience. It’s often easiest to have the boom fully extended, such that small movements at the stand make for big, quick adjustments to the source. But beware that with the boom extended at its greatest reach, the whole rig is at its least stable. Not only should the boom arm be extended directly over one of the light stand’s legs, the stand itself should be sufficiently weighted with sandbags and the boom arm itself should be counterbalanced, either with a sandbag affixed to the hook on the end of the boom arm or with a clamp-on boom weight like the Manfrotto 10-pound counterbalance. These heavy iron weights clamp directly onto the boom arm and can be easily adjusted to balance the load.
Whether using a counterbalance weight or a sandbag, the trick is to distribute the weight such that the light and modifier (softbox, beauty dish, etc.) feel almost weightless when the knob that tightens the boom angle is released. Slide the counterbalance farther from the fulcrum and its affect becomes stronger; move it closer and the source end gets heavier.
No matter how you achieve it—by moving the weight or sliding the boom arm forward or back in its mounting collar—a well-balanced boom makes moving and adjusting even the heaviest studio lighting rigs a snap. And, that leads to better, more precise lighting control, no matter what you’re shooting.