Just like the rest of your dive gear, your underwater camera and its protective housing needs to be kept clean and well maintained to function properly. Taking good care of your equipment will ensure it lasts as long, or even longer, than the manufacturer promises. Here are some tips to help you keep on taking great underwater photos.
Preventing Fogging
Can you imagine getting down to a dive site and shooting a desirable subject you've been waiting to capture with your camera, only to find that your housing has fogged? There are a few ways to prevent this. First off, keep one or two desiccant packets in the housing with your camera, and second, never leave your camera in the sun; anytime you're in the open, keep a damp towel over it or keep it in a specially designed cooler.
When setting up, try to do so inside a cool, air conditioned room to minimize the chances that any moisture enters your housing. When adding the desiccants, ensure they don't get caught on the o-ring, and make sure they're positioned where there is no chance they'll fall onto the lens port.
Preventing Scratches and Damage
If possible, always have your camera rig handed to you once you're in the water, rather than jumping in with it. When you exit the water, get the dome port covered immediately if your camera is equipped with one. Check to see whether a neoprene dome port cover is available for your model; this can help prevent scratching as well.
Do not leave your camera unattended in the rinse tank, and work the buttons and controls in fresh rinse water. Dry it off quickly once it's been thoroughly rinsed.
O-Ring Maintenance
Each day you dive with your camera, clean housing, port, and strobe battery compartment o-rings and grooves and reapply lubricant. Do the same for your sync cord o-rings after every 3 dives or so. Use o-ring lubrication supplied or recommended by your camera's manufacturer, and don't overlubricate.
You don't need any special equipment to do this; a q-tip and a high quality paper towel ought to do the trick. You may need to rinse the o-rings, and if there is any sand or other particulate matter in any of the grooves, you can use canned air or a blow dryer to force it out and prevent scratching. As you're taking care of the o-rings, ensure you do not stretch them since this can seriously shorten their working life.
Once everything is clean, dry, and lubricated, reassemble the camera in its case, with fresh desiccant packs (you can re-use these, just give them time to dry completely before reuse). Give a final look to the grooves to ensure nothing, even a little piece of fuzz, gets caught; finally, close the housing quickly and carefully. Even something as tiny as a hair between the o-ring and grooves can cause flooding, so don't skip this important step.
If you notice a leak while underwater, hold your housing in one position so any water will collect in the bottom, and surface safely, making drying everything a priority .
Taking a Test Shot
The last thing you'll need to do is take a test shot with strobes on, if applicable, inside a dimly lit room. Be sure the resulting photo looks right, and make sure the camera focuses properly. This helps prevent common blunders like forgetting to put in a memory card, forgetting to plug in the hot shoe, or even leaving the lens cap on the camera.
Finally, be sure your batteries are fresh and carry fresh batteries onto the boat with you. Follow your camera's recommended maintenance schedule, and remember to be methodical as you set up and break down your equipment before and after diving. With these simple tips, you can enjoy taking great underwater photos and get the most from your equipment.