Just as your eyes are your windows to the world, a camera's lens enables it to "see" in a certain way. At their most basic, camera lenses are pieces of glass curved and shaped to enable a camera to capture images in a certain way. With compact point and shoot cameras, the lenses are built into the camera and cannot be removed. Once you start looking at lens options for dSLR cameras, a whole new world of opportunity opens up.
dSLR Cameras - UW Photography
Before we get started, here's a definition of dSLR cameras: These are the larger digital single lens reflex cameras professional photographers and serious hobbyists use. They cost more than most compacts, and they come with a camera body and an inexpensive "kit lens" most of the time. You can buy all kinds of lenses, extenders, filters, and other accessories to create excellent photos just like the pros; but before you make an investment in photo equipment, remember that your techniques are going to matter just as much as the quality of your equipment.
Prime Lenses vs Zoom Lenses - UW Photography
There are two basic kinds of lenses: prime lenses and zoom lenses. A zoom lens lets you zoom in on an object without getting closer. These lenses have 2 numbers, like 18-55mm. The smaller number is the wide end of the lens's zoom range, and the larger number is the telephoto end. Prime lenses have fixed numbers like 20mm, 35mm, 60mm, and 100mm. The view is always the same when you look through these lenses: they cannot zoom in and out.
Wide Angle Lenses - UW Photography
These lenses allow you to take a photo of a wide area from a relatively close distance. They are ideal for photographing big wrecks and reef scenes, and they're also great for getting good photos of schooling fish. There are two kinds of wide angle lenses - rectilinear, and fish eye. Fish eye lenses produce images with pronounced curves at their edges, while rectilinear lenses produce images with straight edges.
Telephoto Lenses - UW Photography
You've probably seen telephoto lenses before; these allow people to zoom in on faraway objects and get a crisp shot. Wildlife photographers use them frequently to capture images of birds and skittish or dangerous animals.
Midrange Lenses - UW Photography
Midrange Lenses are a bit like telephoto lenses and wide angle lenses combined. They are also very popular with nature photographers. A good Midrange Zoom Lens is the 17-70mm lens. Other popular models include 17-35mm and 18-55mm. These let you get great photos of big marine life like sharks, turtles, manta rays, and more.
Macro Lenses - UW Photography
These lenses allow you to take extreme close up shots of small subjects, like nudibranchs, gobies, tiny starfish, and other little critters. When you're reading about a dive site and "macro life" is mentioned, then you can be sure underwater photographers who visit the sites use macro lenses to get incredibly detailed and very colorful photos of these subjects.
As you decide which lenses to add to your camera, consider the type of photographs you plan to take most and purchase accordingly. Keep in mind that you may need to upgrade your camera housing when you upgrade your camera; despite this extra expense, you'll be rewarded with great shots you might never have imagined taking. Finally, remember to practice often, even if it is topside. The better you know your camera, the better photographer you will become.