The magic world of Close Focus Wide Angle.
Two basic principles planted in the head of the beginning underwater photographer are: always use an upward angle of your camera, and get as close as possible to your subject. These two rules of the thumb are related to the fact that we take pictures in a tricky medium called water. Since the sunlight comes from above, pointing your camera upwards will bring in more light and contrast in your pictures. For example in the Red Sea choosing a horizontal or a more vertical position means a difference of two f-stops. The vertical position also allows to use a smaller aperture, and thus obtain a greater depth of field.
Light under water The major handicap of the UW photographer is that light under water travels over a much shorter distance than on land. Moreover, small particles floating in the water will make light bounce in all directions, producing less contrast and clarity in your pictures. To make it even worse: in water the warmer colors are absorbed progressively when light has to pass a greater mass of water. The amount of color absorption depends on the total distance of light travelling to your camera: so for a shark at a depth of 3 meters and 2 meters from your camera, light has to travel 5 meters. This holds for sunlight as well as artificial light. That’s why getting close is so important: the closer you are, the better your color, contrast and sharpness will be.
Strobes Strobes can help to restore color and contrast to some extent, but they should be carefully mixed with ambient light to create a natural or more artistic effect. Finding the right balance between the two light sources is the greatest challenge. At least when your purpose is to create an image of the environment as well. Color absorption can be largely restored, but only for subjects at a short distance (< 2 meter) to the strobe. You should also be aware of the fact that small changes in distance have large effects on the lighting of your subject. This is because light intensity changes with the inverse of the squared distance. It will change even more dramatically when you are very close to your subject. For example, if you are shooting a close up of an anemone fish and decide to change your distance from 10 to 20 cm, the drop in light will be 3/4 or two f-stops. Meaning that you need to widen the aperture from f11 to f5.6, or set your strobes at a two times smaller intensity.
The magic of Close Focus Wide Angle That being said, I’d like to mention a technique that has become my favorite on my underwater photography trips. It’s called CFWA, a short for Close Focus Wide Angle. The 'magic' of CFWA is twofold: it comes from the forced perspective and the enhanced lighting and color contrast of the foreground subject, a bit like the 'clair obscur' in Rembrandt's paintings. Although the principle of CFWA is pretty old, the technique has become increasingly popular with more frequent use of fish eye lenses. Alex Mustard, one of its promoters described CFWA in his new book as ‘the most important technique in underwater photography’*. CFWA can be seen as an extension of the mixed lighting technique in UW photography. Mixed lighting has always been associated with wide angle shooting. But the fish eye lens has further expanded the magic of its application. The basic principle is to get very close to your ‘target’, preferably a nice colorful object and then combine a flash-lit foreground with a background illuminated by natural light. Only the fish eye equipped with a small dome lens will allow you to focus as close as 10-20 cm. The revolutionary side of CFWA is that it produces dramatic images that are outside the range of normal wide angle lenses. Mostly by combining two sides of UW photography: ‘near’ and ‘far’ scenes. The pictures show an ultra wide coverage of the underwater world with often dramatic perspective effects. A related technique is Wide-Angle Macro (WAM). Here the photographer gets even closer to his subjects. This is achieved with some adaptations of the position of the strobes like mounting them direct on the housing, and using an even smaller dome port. The more compact your camera rig the better.
Underwater. Photography Masterclass. Alex Mustard. Ammonite Press 2016.