A New Diver's Guide to Underwater Photography
My interest in photography has followed me underwater. I think it was just my third or fourth dive when I first brought a camera with me. Needless to say, every photo was junk. I just didn't have the diving skills necessary to get a good photograph even though I think I'm pretty good with a camera out of the water. Many dives later I've improved my abilities I've discovered a few techniques.
Most of the things you want to take a picture of underwater are moving. This means that it's important for you to be motionless when you take the shot. Eliminating as much motion as possible will make for a sharper image and will increase the chances that your object will be properly framed. That's where buoyancy skills come in.
The first part is lowering yourself to the level of the objecting you're photographing. With fish and crustaceans, you'll likely get the best shot at eye-level. Some shots from above are OK, but nothing beats being at eye-level particularly if the subject is looking into your lens. If you're just starting out, the easiest way to lower yourself is to exhale. And then as you approach your subject you inhale which will slow your approach. At the point of going from descending to ascending you'll be stationary which is when you want to take your picture. You can adjust your camera's position by bending or extending your arms.
If you're better with your buoyancy you can also get close to your subject by "hanging" upside down. Again, you exhale to get close and inhale to keep from crashing into the substrate. This technique is also good for ascending out of tight spaces where you wouldn't be able to kick without hitting something.
Shutter Speed and ISO
My camera, a Panasonic ZS3, has an underwater mode. In this mode, colors are adjusted to account for how light is absorbed by water. This is great, but in other, important ways this mode is not good. Instead, I get better results by switching to manual mode where I can set the minimum shutter speed to 1/250 (if you can go faster, by all means do so) and the minimum ISO to 400 (if your camera can produce noise-free shots at higher ISOs then pick a higher number). Both of these settings work together to improve the chances of getting a sharp image.
I haven't shelled out for a proper underwater strobe so I'm stuck with my camera's built-in flash. I recommend turning the flash off except under the following conditions 1) you're really close to your subject or 2) no flash means no shot.
The problem with the built-in flash is that it will light up particles in the water. So if your subject is several feet away (say another diver) the flash will degrade the image quality by making particles very visible. In addition, built-in camera flashes don't have the strength to reach beyond a couple of feet so you'll just be draining your camera's battery faster.
If you happen to be close to your subject, the built-in flash will bring out more color than without it. For example, a greenish lobster will suddenly become red with a flash. The colors of coral will also be more impressive with a flash, but again you need to be up close.
As a diver you know that using your hands to maneuver is not ideal. With a camera, your hands won't be free so you'll need to get used to not using your hands at all. In addition to your hands, you'll find it helpful to learn a few moves with your fins. First, moving your fins in a scissor-like motion can keep them from kicking up sediment when you're close to the substrate or from damaging corals. Second, pulling your knees to your chest can prevent a crash with the ocean-bottom by buying you a few extra moments to initiate an ascent by inhaling. Third, if you've miscalculated your descent such that an impact is likely, go spread-eagle which will slow your descent from additional drag while also raising your limbs out of the way.
Anticipating the Shot
Most of the fish in my first pictures were turned away from the camera. It turned out that the lag between when I pressed the camera button and when the shot was taken was long enough for the fish to have turned away from me. If instead you can anticipate when the fish will orient itself for a good photo you'll get better results.
Setting the white-balance underwater is tricky. To do it correctly you'd need to place a neutral grey card at a distance from your camera that matches the distance you expect your subjects to be. Good luck with that. For a shortcut, I've use the tank of another diver since it is grey.
If your camera shoots in RAW then you're in luck as you can set the white-balance during post-shot processing without degrading the image. If all your camera's got is JPEG then adjusting the white-balance digitally can still produce great photos, but such adjustments do degrade the image.
Out of the water, a high-powered zoom can produce incredible photos. However, underwater the results are more likely to be disappointing. There's just no way to get around the light absorption of ocean water. So even though you're bringing your subject "closer" you're still including all of the particulate that is floating between your lens and the subject. The only area where a zoom is useful is in macro mode where you can use it to fill the frame with your subject.
That's all I've got for now. I will undoubtedly learn more and I'll happily share my learnings here. If you've had any a-ha moments with underwater photography, please leave a comment!
Chasing is Futile
Crustaceans don't move very quickly and coral, if it's of the soft variety, will only sway back and forth. Fish, eels, and turtles, on the other hand, are typically on the move and much hard to photograph. One thing you'll quickly notice is that if you chase your subject, it will flee. Furthermore, the faster you chase it the faster it flees. One technique that works for me is to drift slowly towards the subject often doesn't spook the creature I'm photographing. And once I've entered the animals "space", I try to become motionless and then wait for the perfect shot.