How to Use On-Camera DSLR Video Lights
Despite the above-average performance of a DSLR when it comes to low-light situations in filmmaking, sometimes you need to add a little more light on the subject, and neither the sun or a light kit is at your disposal. Enter the on-camera light, a continuous-powered light source that has traits similar to the electronic flash unit.
Both sit atop the camera and blare light at the subject. Maybe it's not the best method, but it's often the difference between getting the shot and looking at a murky mess. Effective uses include static shots, interviews, and other darkly lit remote areas. On the downside, it creates a hot spot on the face, it doesn’t cover much distance, and the straight-on lighting shows no depth.
Besides sitting in the same spot, these lights share the same love for the subject as a flash unit thanks to their harsh output and narrow field of coverage. Of course, actual results vary based on subject distance, ambient light conditions, and the specific unit.
Inexpensive models tend to be spectral in output, showing the subject in a pretty unflattering light that acts more like a flashlight than a soft box. But some models are clearly better than others. More refined models include a light control and a wider output. Many of these L.E.D. models produce brighter output with more evenly balanced illumination as well as offering more versatility over intensity.
Even the most sophisticated models, however, lack perfect output. That’s a condition of position as the light hits the subject head on. Unless the subject is framed tight and the camera is at the proper distance from the subject, it can make the footage look like an early morning police raid.
By the way, that coverage range is up to about 10 or 15 feet, depending on the model. Usually, six to eight feet from the subject works best.
Battery life is another issue. Though many lights use rechargeable power, they suck the life out of the batteries faster than that boat in your driveway drains your bank account.
So while they're not perfect, on-camera lights are manageable, providing you know their limitations and behavior.
Consider the following:
Understand the nature of the light source. Some lights offer a very narrow output, whereas others offer wider coverage. Keep in mind that they are bright close to the subject, but the light falls off as the distance increases, so lights work best when the subject is at a fixed distance.
Try to balance with ambient light. After you establish the distance, adjust the light or camera setting so the natural and camera light match exposure. Some lights have a dimmer control, which makes it easier. If not, manipulate balance through the camera-to-subject distance. The closer you match the on-camera light with the ambience of the scene, the more natural it appears.
Consider color temperature. Each model differs in output color, varying from the tungsten-balances 3200K to 5600K daylight. That’s right, some can go that cool. The good news is that most include conversion filters to adjust back to tungsten or daylight.
Use filters for more than correction. Most models include a conversion filter to correct for either tungsten or daylight (depending on the color temperature of the bulb). But you may need to tweak color, and they work best when the subject is at an affixed distance. For those situations, slap on a gelatin filter to slightly modify the tint or color cast.
Filters do more than just change color temperature or hue. They also affect light output, so a light with a filter on it, regardless of the filters intended use, requires more wattage to produce the same amount of light as a light with no filter.