CBL Color Balancing Lens
With all of the attention given to the latest and hottest in camera technology, it's easy to overlook fundamentals (such as proper color balance), which can affect image quality as much as the model and price of your camera. Without adherence to the fundamentals of photography in general, and videography in particular, you won't be harnessing your camera's true potential, whatever that might be. The best lighting and techniques in the world can't guarantee a beautiful picture if your color balance is off.
CBL's Color Balancing Lens. Photo by Carl Mrozek
For many video shooters, color balancing (or more correctly, white balancing), is a fairly mindless—they just aim the lens at a fairly flat white surface, making sure the frame is filled, and then depress the white balance button until the camera lets them know its happy.
Some shooters may not balance again until lighting changes from daylight to tungsten and/or from bright to dim.
If you're shooting outdoors under fairly sunny skies without any supplemental lighting you may get through the day without re-balancing, provided that the orientation of the subjects to the sun is fairly consistent. However, to be safe, you really should re-balance every time the quality or intensity of the light hitting your subject shifts. The question remains about what to use as your white reference.
Some shooters—notably black and white photographers—swear by grey cards. As a result, most camera meters mimic this process (or at least we use this process to evaluate their results). Video shooters tend mostly to use a white card for their balancing.
There's another method which provides both balancing options, and this is the color balancing lens (CBL), a unique patented system for achieving beautifully balanced color images
The CBL is a composite of several thin discs sandwiched together into a thick disk, which is white on one side and grey on the other. The white side is a bit like an ice cream sandwich, with a white vanilla filling sandwiched between two wafers. The bottom layer is the CBL's grey polycarbonate casing, and the upper layer is the clear lens element. The thick white middle layer is really an outer ring with several concentric circular prisms, plus several slightly raised circles in the inner core. Also there are some two dozen geometric slits and grooves arranged in an interesting array of square and diamond patterns.
These overlay a mirror which reflects back the light beams refracted at different angles by the slits and grooves in the CBL's "condensing lens" core. The colored light refracted by the circular prisms is also reflected back to the camera via the two-tiered lens element. The idea behind this is to bend light into many wavelengths, ultimately reflecting all the colors in the spectrum.
The goal of this disk sandwich is to sample the full color spectrum and enable cameras to achieve full color balance, as opposed to the standard white balance based on medium grey, and originally designed for black and white photography.
The CBL is supposed to work particularly well with SLR cameras, and claims to be the only light balancing device for digital cameras using "full color balance" methodology. The unit's grey side is made up of 13 different materials selected to produce the most consistent and accurate color balance feasible in direct sunlight, and also under studio lighting.
The CBL comes in four sizes: 220, 110, 85 and 60 mm. All but the 220 mm size fits easily into a coat pocket, even when protected in their velour carrying pouches, and are easy to pack along when shooting.
The CBL kit includes a compact pocket guide for the lens, with tips for using it effectively under many conditions and with different cameras. (There's a separate section for DSLRs too.) The guide includes a number of color photos that compare balancing results of the CBL vs. standard white balance and grey card methods.
I tested the 110 mm CBL which is geared for a broad variety of cameras from DSLRs to various Pro HD camcorders. I used it mainly with a Canon XL H1 HDV camcorder equipped with the Canon 20X lens and a 1.5x extender from the 16x9 folks, as well as with a Canon 28-300 mm digital still lens adapted to the XL H1 with Canon's EF-XL mount adapter. For much of my evaluation I shot wildlife at the higher end of the tele range, with color balanced for bright daylight, as well as for sunset and some in-between conditions. Initially, I was careful not to alternate between the CBL full color-balance reading and the balance done with a white card, until it became apparent that there was little difference in most shooting situations. However, by the time the herons were flying to their night roosts, the color temperature got noticeably hotter and redder, and I did rebalance to keep the foliage crisp and green. It was then that I found the results with the CBL device were consistently more natural looking and reliable. Hence, I mainly used the unit during evening hours, as it did a better job of averaging the extremes of light then, including the hot reds of the setting sun and the blues and magentas of back lighting.
I found that I could rely on the CBL unit to help avoid color shifts, particularly in the green region where such shifts are most obvious. And as I was capturing to HDV, I really wanted to avoid color correction and any additional processing that might affect image quality. The consistently accurate readings obtained with the color balancing lens helped me do that with a few exceptions. One of these was when I hurriedly rebalanced with the subject about two feet from the lens and I couldn't see the image clearly in the viewfinder. (I probably filled less than the recommended 60 percent of the frame).
The CBL unit excelled in mixed lighting conditions. I tried it with various combinations of tungsten, fluorescent, daylight LEDs and daylight color temperatures, and consistently came out with better flesh tones and more natural colors. (They often seemed slightly warmer, but appreciably more natural looking.) This was particularly true at low light levels.
For the most part the CBL color balancing lens performed as advertised, delivering "natural looking" color-balanced images under most lighting conditions. However, it performed best in mixed lighting environments, regardless of the color temperature blend, and consistently eclipsed the results obtained with a simple white card. However, in comparing the CBL balance to standard white balancing techniques in "broad daylight," or with plenty of LED or tungsten lighting indoors, both often yielded identical or nearly identical results. I did have one slight issue with the device though. This was when I was shooting around sunset, with the sun's rays at a very low angle. As I was shooting alone, I had no way to elevate the CBL off the ground by the three to four feet needed to get above vegetation level and out of "deep shade" conditions. The unit does come with a strap which could be attached to a pole with arm staked into the ground, but that's another gizmo waiting to be devised.
The CBL device's consistency and superior performance in mixed lighting—along with its extreme portability—still makes it a handy accessory and one that serious cinematographers should consider. This is especially true if you want to avoid extensive and meticulous color correction in post production. The device is cheap insurance against having to do so; but don't expect it to operate like some kind of a magic wand. Fundamentals of photography and common sense still apply.
Carl Mrozek operates Eagle Eye Media, based in Buffalo, N.Y., which specializes in wildlife and outdoor subjects. His work regularly appears on the Discovery Channel, The Weather Channel, CBS, PBS and other networks. Contact him at firstname.lastname@example.org