How do the pros get their blues so very blue, and how do they create those images you practically drool over every time you log onto your favorite websites? The answer often lies with the use of simple filters designed to make certain colors really pop. Let's take a look at some basics for using filters to enhance underwater photographs.
Filters Change the Way Your Camera Sees Light
One of the most important aspects of underwater photography is the interaction between light, which allows us to see colors, and water, which blocks some colors while allowing other colors in the spectrum to pass through. Filters enhance light so you can get the photos you want.
Now that digital photography has all but completely replaced traditional photography, and electronic white balance has made obtaining true colors much easier than before, some naysayers try to tell us that filters are an unnecessary encumberment. Exactly the opposite is true. In fact, there are two classes of filters that make underwater photos much more compelling.
Color Compensating Filters
Also known as CC Filters, color compensating filters are used to either select or favor a certain subset of the spectrum. These filters come in two varieties - warming, and cooling. Warming filters are most commonly used in underwater photography since they warm up the cool colors typically encountered in aquatic environments. One of the most common is a magenta filter; professionals layer between 2 and 5 units of magenta filtration for each foot of water, with cloudier water requiring higher levels of color filtration. The filters are available as gels that you have to combine and mount yourself. The benefit though, is that experienced photographers can create special filters for a unique look.
Fluorescent Filters
First designed to deal with the effects of fluorescent lighting, which typically casts a slightly green shade, fluorescent filters are quite a bit easier to work with than gels. They're typically available as thread-on and rectangular styles in a number of combinations. One of the best sources for these filters is UR Pro, which develops and produces filters designed specifically for underwater photographers.
Choosing the Right Filter
First, your decision will need to be based on whether the water you'll be diving in is blue or green, plus it should be based on whether you're diving in deep or shallow water. FL-D type filters are suitable for green water and shallow depths above 20 feet, while FL-B type filters are better for blue water and depths between 20 and 70 feet.
Lenses with rear gel holders allow you to create your own filters. You start with magenta gels, then add warming gels, like 81C, 81EF, and 85, which bring the balance of light closer to matching the imaging sensor's optimal balance. You can use a strong warming gel on bright days or deep dives; otherwise, you might want to try some shots with a weaker gel or no gel at all.
Lastly, look into magic filters if you're new at working with filters. They are available in formats for blue or green water, and in configurations for dSLR or compact cameras. If you're using a compact camera, try using magic filters for better color, even if you elect to use no strobes or other light sources.
Using filters while shooting underwater photographs is a way to express yourself more artistically and capture the wonders of the underwater world. As such, there are no real hard and fast rules for using them, except to work to achieve the colors that please you most, and to shoot as many photos as possible to become more experienced. The more you shoot, the better your skills will be!