Use a Strobe
Though not always necessary, strobes can really make a huge difference to your underwater photographs. A strobe helps introduce light thereby adding true colors to your photographs and reducing that blue/cyan hue on all your pictures. A strobe also helps freeze motion, and get higher shutter speeds from your camera, which is crucial while photographing skittish fish.
Go Digital
The underwater digital cameras can be the greatest thing for anyone starting out underwater photography as it can be very forgiving, allowing the diver to take multiple shots and play around with settings to experiment and get that perfect shot. Digital cameras also allow you to instantly review the image which helps determine if your composition is right, which is very difficult to do using a cameras tiny viewfinder wearing a dive mask.
Stay Shallow
For the best underwater photographs while starting out, stay shallow, where the light from the sun penetrates the most to get the best photographs. The shallower you are the less light gets absorbed by the water, giving you more light to work with and results in more colors in your pictures. Most underwater photographers won’t bother carrying their cameras with them on a deep dive unless they have powerful strobes with them.
Get in Close to your Subject
Perhaps one of the more common tips for underwater photography for a good reason too. While underwater, get in as close as you can to your subject, and when you think you’re close enough, get in closer. The reason for getting closer to your subject is because water is 800 times denser than air, and the further you are from the subject the bluer your photographs get. If you are using a strobe, then by getting in close, you capture the best details, get the most light and reduce the chance of any debris causing backscatter.
Use a Color correcting filter
A secret tip to get better looking photographs is to use underwater color correction filters on your camera, which are essentially red filters which can be screwed onto the front of your camera’s lens that corrects the color balance by reducing the cyans or Blues in your pictures. Choose a filter density according to the depth at which you will be photographing and the color of the water, ranging from dark blue to green.
Take pictures when the sun is overhead
In order to get the maximum light into your pictures, shoot while the sun is directly overhead for the best natural lighting photos. The reasons for this is that the light refracts off the surface of the water when the sun’s light is angled, and only a part of the light enters the water. When overhead, the suns light entering the water is the greatest. Even so, using a strobe or fill flash in addition to the suns light will help improve your photographs further.
Learn proper Buoyancy Control
One of the biggest tips for anyone wishing to do underwater photography, is to master Buoyancy control first. The secret to all sharp photographs is steady hands and no camera shake. The only way to achieve this underwater is to be absolutely stationery and hover using breathing techniques. For those that have not learned to control their buoyancy, your only chance is to take photographs while resting on the sea floor or using their camera burst mode to get as many photographs as they can and hope one of them turns out ok.
Minimize Backscatter
While using a Strobe underwater, one of the most annoying things is backscatter. Backscatter refers to the reflection of suspended particles or debris underwater which turns up on the photo as a bright spot. Backscatter can be minimized by using a strobe arm and aiming the stroke top down, so that the particles don’t get illuminated front of the lens. Backscatter can also be minimized by shooting against a busy background or reducing the distance between the subjects.
Post Processing
One of the best friends of an underwater photographer is computer post processing. Using a good image editing software, you can add filters, correct color and reduce that annoying cyan tinge bringing out the true colors of things. Imaging suites also help get rid of backscatter using the spot correction tool. A post processing software can magically enhance any of your underwater photographs, but is still no substitute for a sharp well taken picture to begin with.
Shutter Speed
Setting camera shutter speed is always a tricky issue when dealing with underwater photographs. If you set the shutter speed to low, you are going to get more light in but blurry subjects. If you set the shutter speed too high, you will freeze motion and get beautifully detailed pictures, but not enough light, and that annoying black backgrounds. The trick is to use a high ISO setting, a powerful strobe and a medium shutter speed that will capture enough ambient light without blurring the subject.
Source: Aquaviews