Education Underwater Video Articles The Importance of White Balance
The Importance of White Balance |
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Although in The Camera Coach, Your Guide to Creating Underwater Video, I discuss the importance of white balancing your camera, I use a plain white slate. Since I created
The Camera Coach I had the pleasure of working as an assistant to Tom Campbell,
Underwater Cinematographer extraordinaire! I learned a lot from
this experience. As I continue to learn, I want to continue to share with
you. Tom Campbell took the time to explain the differences between
white balancing off a white slate and white balancing off the DSC color
chart. It is with his agreement that we share his knowledge with
you. Tom recently wrote this article.
If you have any questions, please feel free to contact me: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
As a marine wildlife cinematographer who spends much of his life in, around, or underwater, I confront a number of challenges not so common to those that land or surface cinematographers face. Those of us who shoot u/w or topside anywhere around the ocean encounter more precarious situations with regards to caring for our equipment. We also experience a wide variety of lighting issues that must be learned in order to get top quality HD images of marine wildlife. Paramount to capturing precise color match and exact contrast in the marine environment begins with acquiring the correct and most accurate white balance. Color saturation is totally altered with the bending of light rays as they enter the water column from the angle of the sun. The amount of light is again affected by the amount of turbidity or particulate matter in the water. Color saturation is further altered by such things as wave action on the surface, the number of clouds in the sky, and it just gets worse. As you descend deeper in the water, the lack of light coming into the water column dramatically affects the color spectrum of brighter colors such as reds, greens, yellows, etc. In the first few feet of depth, bright red objects start to lose their true color and become a drab brown by the time you reach 30 feet or more. Orange and yellow colors drop off next as you approach the 60-foot depth. Blue can be distinguished to 100 feet and greens fall away too, until - eureka! You’re left with a very monochromatic and drab looking topography with dull-colored fish life that wouldn’t capture anyone’s interest for long. If you cut yourself underwater or you spear a fish at these depths, the color of the blood will appear green rather than red. It’s not just vertical depth that causes this effect: once you’re at the depth you have chosen to shoot the horizontal distance also causes loss of color. For example: A diver shooting in just 10 feet of water with a subject 10 feet away will have filtered out nearly all the warm colors because the light now has to travel 10 feet down and 10 feet out which equals 20 feet. Horizontal color loss is the reason that u/w lighting systems are not very effective if not used properly. Most strobe or constant lighting systems will reach out 6 to 8 feet effectively but offer very little illumination beyond that distance. So the photographer at 10 feet of depth and 10 feet from his subject is going to get little to no color because not many lighting systems will reach out 20 feet. Whenever you see an underwater show that has brilliant colors in it you can generally assume it was shot either with lights of some sort or the perfect white balance chart. Is there no hope? Yes there is: In working as a professional u/w photographer and cinematographer for nearly 40 years now, I have learned many things about lighting, both from the years of experience (the hard way!) and from other experienced shooters in the same field. My crew and I may have a bit of an edge on High Definition work in the water considering that we switched from film to HD over 9 years ago, before HD became a household name. For us, the answer to getting perfect color saturation both top side and u/w with our HD Sony F-900 cameras and the smaller format Sony HDV HVR-Z1U camera is to use the correct DSC chromadumonde color correction chart. While many models of the chart are available, four of them suit our specific needs, which makes it easy for us to have one for u/w that is smaller and easier to swim with and a larger one for topside work. The DSC Company has pretty much pioneered the field in establishing the exact mathematical formulas for their DSC charts by using spectrophotometers and waveform vector scopes. They have established precise white balancing charts to match color combinations, which achieve perfection in producing correct colors. The old days of pulling a white balance off of a white plastic board, walls and t-shirts are pretty much left to history, or amateurs, as it may be. If you consider any other source of white balance, you are paying the price for manufactured materials, which have any number of UV inhibitors built into them, which will throw color off considerably. In fact, white boards or other white-colored materials will generally give an IRE (incandescent ray emulsion) reading of somewhere around 8 or 9, as compared to the proper chromadumnde chart, which will give about 100 IRE. The IRE is a direct relationship to the color saturation; the higher the IRE value, the truer the color saturation. Therefore, choosing to use a DSC chart over a white card is not rocket science for us! Considering that everything we shoot is in HD, which allows the most vibrant and real life colors possible, we simply cannot afford to have anything less than perfection in today’s competitive work place. When white balancing underwater, we try to get as close to the chart as possible, to avoid the problems of refractive light loss as mentioned earlier. We fill the frame with at least 70% of the chart with an equivalent light source in which we’ll be shooting, in order to give us the best saturation and precise color match possible. For u/w menu settings we have had a UR-Pro filter installed in the color wheel in the ND-4 position by BandPro in Burbank, which puts a tad more red into the mix if needed. When using the smaller HDV camera we can white balance at any depth with the DSC chart we have chosen and get match colors on tape. It is important though to re-white balance as you descend deeper to take into account the continued loss of available light, especially if you are not using an alternate light source. Once we establish an accurate white balance we program the setting into the menu and capture it on a memory stick. We lock in settings that are aligned to other lighting situations we use such as the powerful HMI lights, which are for lighting large subjects and wide-angle shots. We also use a smaller lighting system for macro work and yet another setting for natural ambient light with no artificial lights. Using the DSC chart to white balance for each situation, programming those results in the menu, and checking the white balance with our chart underwater allows us to achieve stunning results. The true kaleidoscope of colors found beneath the sea are far more impressive than those found anywhere else on earth and only through proper white balancing can they be captured in all their brilliance.
www.anniecrawley.com
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