Though today's video cameras are very light sensitive, many scenes require you to use artificial lighting; Most notably wrecks, caves, night dives, murky water, diving in Monterey etc. Artificial lights will not only brighten areas where ambient light cannot reach, they also restore color to otherwise monochromatic footage. There are two types of underwater lights you can use, Tungsten Halogen and High Intensity Discharge (HID). In the following article I will cover the pros and cons of each light system and help you decide what system is best for your needs.
High Intensity Discharge (HID)
HID lights are daylight balanced or 5500k. This makes them easy to color balance against ambient daylight. There is no obtuse tonal change between the sunlight in the background and the artificial light in the foreground.
Because of this, I like shooting HID in wide-angle tropical settings where a good amount of ambient light is available. Artificial HID light can then be used as a fill rather than the only light source. The consistency in color temperature, 5500K for daylight and 5500K for HID, allows for more subtle lighting techniques.
HIDs are also much brighter and have a wider beam than halogen lights. They give roughly 3x the light output per watt of power than halogen. Therefore, a 35 watt HID light will give the equivalent light output of a 100 watt halogen light and a beam angle of 110 degrees, as compared to the 35 watt light at 60 degrees.
- 1600 K: sunrise and sunset
- 1800 K: a candle
- 2800 K: Halogen or Tungsten lamp (ordinary household bulb)
- 3200 K: studio lamps, photofloods,
- 5000 K: standard for professional light booths, photography, and graphic arts.
- 5200 K: bright midday sun.
- 5500 K: HID Lights, average daylight, electronic flash.
- 6000 K: lightly overcast sky
- 6500 K: heavily overcast sky
- 8000 K: hazy sky
- 20000 K: deep blue clear sky
Color Temperature is the standard by which all light is compared. In film and video it is directly related to how your camera sees light as a color tone.
Halogen lights have a color temperature of 3200k and are therefore warm. Many videographers prefer the tone halogen lights bring to blue underwater footage, but color-balancing halogen light with sunlight can be a challenge. The warm halogen lights in the foreground will contrast with the blue ambient light in the background. Those shooting wide-angle subjects in bright environments may prefer the daylight balanced HIDs. I personally like halogen lights when shooting in Monterey because the water here is normally dark and green. Balancing artificial lights with natural sunlight isn't really an issue. In macro scenes balancing foreground light with background light is not an issue.
Another feature I appreciate in Halogen lights is the adjustable power output. Most have 3 settings giving me the flexibility to add more or less light as I choose. There is however, a drawback to this flexibility. Halogens use a heated filament to produce light. This heated filament will eventually burn out like any normal bulb. A 30w halogen bulb has a typical lifespan of about 40 hours where an equivalent HID bulb will last around 300 hours.
Mounting Your Lights
Once you've picked a light system for your housing you must be able to mount the light heads and their pods to it. We at Backscatter recommend you purchase a housing package that includes both the housing and the light system. This is not only convenient, but cheaper in the long-run. Otherwise, most light heads can mount to housings using Ultralight or Infinity arms. Mounting the pods to the bottom of the housing is the challenge. Light and Motion provides an extra plate to attach their battery pods to other housing brands. Gates does not and modifications may be required to mount their batteries to another brand of housing.
Here are a few direct links to Halogen and HID lights I recommend.
Light & Motion Sunray-S Mini Pro HID Video Lights
Light & Motion SunRay S Halogen Video Lights
Light & Motion SunRay S HID Video Lights