Whether you're brand new to diving or if you've been logging bottom time since the days of the aqua lung, it's natural that you are interested in learning the basics of underwater photography. More divers are taking photos now than ever before, mostly because today's digital technology is making underwater photography easier than ever and much less expensive to pursue. While you could get a simple point and shoot camera and call it good, you may be interested in taking better shots. Whether you've already purchased an underwater camera, or if you're still in the market, understanding underwater camera terminology can help you get the right camera and take advantage of tips for underwater photography. Here are some basics to help you get started.
Lenses
Lenses are the optical pieces of glass that focus the images as they enter the camera. On more advanced cameras, lenses can be removed or changed. On a compact camera, the lens is integrated into the camera's design and cannot be removed.
Shutter Speed
A camera's shutter opens and closes to control the amount of light that is let in. The longer it's open, the more light comes in. Shutter speed refers to the length of time a camera's shutter remains open.
Aperture and F-Stop
These two terms are used interchangeably. The aperture is an adjustable opening inside the camera lens. Much like the pupils of your eyes, the aperture allows in a certain amount of light depending on the size of the opening. F-stop is a measure of how much light the aperture lets in. It is expressed as a number preceded by the letter F, like F2.0, F4.0, F8, etc.
One very important thing to remember is that the lower the number, the more light is allowed in. When you close your aperture (called stopping down), you go from a lower number like F2.8 to a higher number, like F4. When you open up your aperture (called opening up), you go from a higher number to a lower one.
Depth of Field
Also known as DOF, this is the amount of the photo that is in focus. A photo with a large depth of field has a crisp background, while one with a small depth of field has a blurred background.
ISO
ISO refers to your camera's sensor's sensitivity to light. Most camera sensors have optimal ISO settings of 100-200. When you raise the ISO you increase the sensor's sensitivity to light.
Exposure
Exposure is the amount of brightness seen in a photo. Good exposure results from a combination of shutter speed and aperture, ISO, and flash power that provides the brightness level you want to see in your photos. Once you learn exposure basics, you can use exposure to create interesting effects within your photos.
Strobes and Flash
Strobes and flashes are simply methods of adding light to the scene to compensate for the dimness of the underwater world and to make colors stand out. Using strobes and flashes properly can help to ensure you get great color when you want to.
If you have TTL, your strobe and flash power is automatically adjusted, either by the camera, the strobe, or by another piece of electronics. Without TTL, you must set strobe power yourself.
White Balance
Your camera uses white balance to interpret the colors in your photo. Using different white balance settings can result in photos that look bluer, greener, or even more orange, reddish, or yellowish.
Now that you know a bit more about underwater camera terminology, get out there and start taking some photos. The best way to improve your technique is to practice, even if that means practicing topside. Work in a dimly lit room to simulate underwater conditions, and memorize your camera's functions. Just like any other tool, it does its best work when you know exactly how to use it.