The ocean is a dynamic medium that supports billions of organisms, from bacteria to blue whales. Its ever-changing design has attracted man since the beginning of time and continues to inspire artists of all kinds. With recent advances in technology, including sophisticated waterproof housings and strobe lights, we are able to capture the complex and variable system that thrives beneath the ocean’s surface.
• Light Underwater The first thing to consider when entering the realm of underwater photography is the difference between properties of light in water versus air. First of all, the ocean acts as a giant light filter removing available light and altering the light spectrum. The red end of the spectrum is lost first and other colors disappear in sequence as you get progressively deeper in the water and further from the light source. Artificial light sources may be used to capture color lost at depth. Water also acts as a lens, magnifying the objects you observe underwater. The refractive index of water is 1.33 (as opposed to an index of 1.0 in air) meaning that objects under water appear closer than they actually are. This alters a photographer’s perspective and must be kept in mind when composing a shot. In addition to these unusual properties of water, backscatter may also appear in photographs taken underwater. Backscatter refers to specks, spots or blotches that may show up in photographs due to reflection of strobe light bouncing off of particles in the water column. Be conscious of this when using an artificial light source. One feature of light that can easily be seen if you look up towards the sun from an underwater perspective is known as Snell’s Window. The light filters through the water as a bright concentrated circle directly overhead, while all the water outside the circle is darker. Shots taken up into Snell’s window are best when the water surface is calm and can produce nice profile shots of macrofauna. (insert photo of Snell’s window) The unusual behavior of light within the water column makes underwater photography a challenging genre. Using an artificial light source underwater is often essential due to the lack of natural light that is available at depth. Flash allows the photographer to capture subjects that do not have ample lighting so that they do not appear dim or dark in the resulting photograph.
• Things to Consider Before heading into the water to photograph, there are many factors to consider. First of all, decide whether you will be photographing via SCUBA or snorkel equipment. While snorkeling may limit what you can shoot, the light is best in shallow water and less equipment is needed. Keep in mind any safety issues that may arise in the dynamic environment in which you are shooting due to changes in tides, waves and wind action. Also keep in mind the time of day and how much ambient light will be available. If you are planning a night dive, be sure to have an appropriate light source to illuminate your subject in the dark environment. Turbidity and visibility in the water column must also be considered so that backscatter can be minimized.