While there can be no denying the value of flashes and strobes, there is definitely something to be said for underwater photos that use ambient light as their only source of illumination. In fact, most wide angle photos, especially those taken from a distance, turn out best using ambient light only.
Camera Menus and Ambient Light Photography
When you look at your camera, you'll probably notice a whole host of menu items and lots of different metering modes, not to mention at least a few shooting modes. Despite this, when it comes to shooting with ambient light, you've only got to remember the basics and you'll be all set. There are three controls you'll be using to regulate ambient light exposure and create amazing images. Those are: Aperture, ISO, and Shutter Speed.
Settings to Use
The way you set up your camera will make all the difference when using ambient light with underwater photography:
- White Balance - use daylight or a cooler white balance setting most of the time. Avoid automatic white balance mode as your colors will not remain consistent throughout your photo set.
- Metering Mode - use a small weighted meter or a spot meter if possible. While matirx metering works very well with other modes, it doesn't provide the control you need for shooting with ambient light.
- ISO - Set ISO according to conditions and your camera; most of the time this will be either at or near Base ISO. Try 100 or 200 to start with.
- Exposure Mode - Use manual exposure mode to gain full control over your images.
- Aperture - A setting between f5.6 and f8 normally works best.
- Shutter - Set your shutter to 1/125 to start with, then adjust as necessary.
Achieving Color
Once underwater, it's time to use manual exposure mode to get the color you want. If the sun is going to be included in your images, meter 15 to 20 degrees from its' center, and if not, focus on an area of water near the center of your image to meter off of. Set your controls to zero out the light meter by choosing to meter off the background color that appeals to you most. You'll probably be underexposing by 1 to 2 stops most of the time to achieve the blues and greens you like best. Practice by shooting nothing but water until you can achieve consistent color, then move on to working with shooting silhouettes.
As a rule, you'll end up with the most color in shallow shots. Keeping the sun to your back will allow natural light to fall on the front of the subject, and using color enhancing filters will compensate for any lack of brilliance in your colors, particularly if you're working with portraiture or taking macro shots using ambient light only. If it is impossible to do this, meter on a neutral portion of your subject, such as part of a wreck or rock wall. While background colors may be lighter, you can still get interesting images and later, you might find that they work very well as black and white images. By taking these steps you can get some great shots and become a better underwater photographer, besides.