By Marty Snyderman
"I'm just getting started in underwater photography and am confused about what film I should use. Some of my friends suggest that I use a fast film, one with an ISO of 800 or higher. Others tell me slower films are better. Who is right?"
This question, asked by Chad S. of Evansville, Indiana, summarizes a dilemma that perplexes many beginning underwater photographers. So, let's take a look at which films work well in underwater photography and why.
Because there is less sunlight underwater than at the surface, new photographers often conclude that they will need a relatively fast film in order to get a proper exposure. However, in typical sport diving settings this is usually not the case. One of the fundamental differences between creating photographs on land and underwater is that a key to success underwater is to get very close to the subject. Getting within a few feet allows you to shoot through as few suspended particles as possible and to use a strobe effectively.
Using a strobe means you will not be depending on sunlight alone to expose the subject. In essence, you control the light level.
A strobe performs two tasks simultaneously. It paints color into the photograph and provides light for exposure. As long as you are no farther than five feet from the subject, most strobes made for underwater use are powerful enough to give you a proper exposure if you shoot with an ISO 100 film. Some more powerful strobes can work well with a strobe-to-subject distance from as far as eight feet.
It is important to realize that a fast film and a powerful strobe will not help you shoot through murky water. If your eyes can't see your subject, your film has no chance to record a pleasing image. Fast films such as an ISO 800 also produce grainier images and tend to render less pleasing colors.
In typical underwater shooting scenarios, as long as Chad has decent visibility and a strobe, he will probably be far more pleased with the sharpness, small-grain structure and colors in images produced with slower films. When shooting slides underwater, I find Fuji Velvia, an ISO 50 speed film, to be an excellent choice for close-ups, and Provia 100 and Echtachrome 100SW to be better for scenics and wide-angle shots of my diving buddies and larger marine creatures. Kodacolor Gold 100 is an excellent all around choice for prints.