Shutterbug with Greg Rothschild

White Balance and Your Aquarium

One of the most common questions asked in the Photography Forum on Reef Central is, "Why are the colors wrong in my aquarium pictures?" This article will attempt to answer that question and provide information that will help you take aquarium photos that look "just right."

The first thing to remember is that different light sources emit different colored light. One measure of overall light color is "color temperature" and the standard unit of measurement is kelvin. Color temperature refers to the color of light produced by a black body (think of this as an iron sphere) that is heated to the given temperature, and kelvin are nothing more than degrees Celsius or Centigrade with the zero point at absolute zero, -273.16 degrees C (or - 459.69 degrees F). Using some measures "normal" daylight is approximately 5,600 kelvin - usually referred to as 5,600K. Common light bulbs like the ones that probably are in lamps throughout your house are incandescent (usually producing light from heating a tungsten filament) and typically have a color temperature near 3,200K, which is very yellow/warm in color. The lower the color temperature, the more reddish or "warmer" the light. Have you ever noticed how warm the light appears at sunrise? It's nearly the same color temperature as a tungsten light. At midday it's much bluer, cooler, at roughly 5,600K. An overcast sky is even cooler (around 7,000K), and if you pointed your camera straight up at a clear blue sky, you'd get a reading of roughly 9,000K.

Those are all common color temperatures and our digital cameras have no trouble accurately rendering photos taken in their light. Where we run into trouble is with actinic and metal halide lighting; it's far bluer than anything a camera normally encounters. Just about every digital camera available, no matter how inexpensive and fully automatic, can take outdoor photos with accurate color, because the color temperatures outdoors are rarely below 3,000K or above 10,000K. But in our aquariums? Getting a good picture from them is much more difficult, indeed, as most of us have discovered. The reason digital cameras have trouble with our tanks is that the white balance circuitry in most of today's cameras is not programmed to deal with light that is far beyond 10,000K. So, if you're having trouble getting accurate colors, and you're using 20,000K metal halide lights, that's why.

So what does selecting a white balance actually do? In the most basic terms, it tells the camera what white looks like under a specific light source. Once the camera knows what white is, then it can calculate how all the colors in the image are supposed to look.

If you're having trouble getting accurate colors under extremely blue lighting and your camera does not allow you to manually set the white balance, try using the bluest white balance preset, usually the shady day setting. That gets you as close as your camera is capable of getting; the next step is to work on the photo in an image editing program such as Photoshop or Irfanview or one of the many graphics programs available, where you can try to remove the blue color cast. If you burn 20,000K lamps (or even 14,000K) over your aquarium and want to take accurately colored pictures of corals and fishes, consider investing in a camera that allows the white balance to be set manually - it will make your life a lot easier.

Different camera models use different steps for manually setting the white balance. Consult the manual for the steps necessary for your particular camera. After you're familiar with which buttons to press and in what order, you're ready for the next step: taking a picture of something white with the light source hitting the white object directly. Find something that is white (the lid of a kalkwasser container or similar white plastic lid works well since it's plastic and won't be harmed if it gets wet nor will it harm the tank), and hold it under the aquarium lights so that it's completely lit by the same light that is lighting your tank. Then take a photo of the white object.

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Don't worry if it's not in perfect focus; the main thing is that the source light is covering the white object. Consult your camera's manual for the proper procedure for selecting the image that you just took to be used as the reference for the manual white balance. Once that's done correctly, everything shot under those lights should be properly color balanced and the images should look accurate. Theoretically. In reality, it's very likely that some small color adjustments still will be necessary… such is the reality of digital photography.

If you're lucky enough to own a camera that has the ability to shoot raw files, I highly recommend using it when taking aquarium photos. Raw mode is ideal for aquarium photography because the images have not been adjusted by the camera at all: no color adjustments, tone, contrast, sharpening, etc. All of those adjustments are done on the computer with special software made just for that purpose. The beauty of raw mode is that the white balance is set after the image is made. This allows a great amount of flexibility and is a huge blessing for those of us with extremely blue lighting over our tanks. With most raw conversion software the white balance actually can be set by color temperature. Combine that with minor adjustments in the green/magenta and blue/yellow channels and you can usually get accurate colors from even the most photographically challenging tanks.

If you have any questions about this article, please visit my author forum on Reef Central.

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White Balance and Your Aquarium by Greg Rothschild -