What you Need for Underwater Photography
Before you can do much with these rules, you need appropriate hardware. At the least expensive end of the spectrum, you can buy a disposable waterproof film camera with a flash for under $20, and then scan the resulting pictures. The most expensive end of the system requires a DSLR camera (minimum $500) and a custom underwater case (often more than $1,000). I chose the middle ground – a compact digital camera and matching case from Canon.
Canon may not be the only camera manufacturer that makes its own waterproof cases, but they’re certainly the least expensive. They don’t sacrifice quality, however, as their cases are every bit as sturdy and feature-complete as the expensive 3rd-party ones. I use a Canon SD700 IS - it’s no longer being sold, but Canon has other models with more features at better prices. My current recommendation is the SD1000, which won PC Magazine Compact Camera of the Year (2007). It’s available at a very reasonable price ($159 at Amazon), and its corresponding underwater case (WP-DC13) is also available for a reasonable price ($168 at Amazon). The case is good to the range of 100-120 feet deep, which is about the range for standard SCUBA diving. Some cases are only good to about 10 feet deep – they’re OK for snorkelling but not diving.
The first thing you need to do is practice inserting the camera in the case and closing the case successfully. All cases like this have a giant “O-ring" seal, and this ring must be in perfect condition or it will leak. Even a small hair in the wrong place could introduce a leak. You need to practice installing and removing this rubber ring, and learn to smear it with a tiny amount of petroleum jelly to help get the best seal. Once you have the case closed, you’re ready to test it. Immerse it in water, with the lens pointed up…if any water leaks, it should accumulate at the back and not get into the camera itself. While the camera is under water, press all the buttons to make sure they do not leak.