In July, I attended a session by Empire Divers, called “Getting Started in Underwater Photography with Larry Cohen.” Larry is the resident expert in underwater photography at B&H, and really knows his subject. As a diver and “advanced beginner” UW photographer, I had a lot to learn during the 2-hour presentation.
Get a proper underwater housing for your camera.
Don’t make the mistake of getting the camera before you know whether there are housings readily available for it. Make sure that all of the controls of the camera are available when the camera is in the housing, and that you can actually manipulate them when diving. (Cold water gloves make for thick, fumbling, fingers!)
Note, too, that the ‘port’ through which your camera sees has to be compatible with the lens(es) you intend to use. If your camera supports changing lenses, be sure that your housing’s port can either support them all, or that you can change the port, itself, to accomodate the additional lenses. Lastly, keep your housing clean and in good repair, especially the O-rings!
A larger CCD means a higher quality image.
The larger the camera’s image chip (the CCD), the more light it can take in, resulting in higher quality images. Contrary to popular belief, the number of megapixels (pixel count) is *not* equivalent to the image size; more pixels in a smaller image is actually detrimental to image quality in low light situations (like under water).
Point and shoot cameras (with an appropriate housing) are fine for taking many pictures
They’ll often be a less expensive alternative to DSLRs, too. However, they generally have a number of limitations that will affect the kind of pictures you can take:
- Point and shoot cameras tend to have a more narrow F-stop range (typically less than F8), narrowing your depth of field.
- They generally support very limited, if any, manual intervention, e.g. of choosing shutter speed, or F-stop, or both.
- They tend to have smaller image sizes.
Use flash to control the lighting of your subjects
This both increases the light available, shorten the exposures, and replaces colors missing due to the filtering effect of the water. However, you don’t want to use the built-in flash on your camera for lighting a scene. It’ll reflect off the inside of the housing, causing flares in the images and playing havoc with the exposure, and will also cause backscatter (lighting up flotsam and jetsam in less-than-clear water) which obscure your subjects. Instead, you should use one ore more strobes, positioned to the sides, above, and/or below the camera. These will be synchronized with the camera, either electrically (via electrical cables) or optically (via fiber optic cables, or optical sensors), and are usually mounted on flexible arms that allow you to position them to get the best results.
Use wider lenses, and get close!
The wider, the better, especially for larger subjects. Closer is better when using a macro lens and/or smaller subjects – you’re within in inches, rather than feet, of your subject. As with a flat (planar) mask, a flat (planar) port will magnify the view by about 33%. This means that the use of a (35mm equivalent) 50mm lens will result in an image equivalent of the use of a 67mm lens. So, compensate either by using wider lenses, or by using a dome port.
Play with the shutter speed to highlight the subject
The flash will generally cause the foreground to be well exposed, but whether the background is dark or light will depend on the exposure time; the faster the exposure, the darker the background.
Play with additional (optically fired) strobes, e.g. to light a subject from behind.
This can be especially useful in dark, closed-in environments (like wrecks and caves).
Practice, practice, practice.
I’m sure I don’t have to tell you that. That’s the fun part!