Here are some basic underwater photograpy tips for beginner photographer.
1 Get close to your subject - preferably within 12 inches. Water reduces color, contrast, and sharpness
2 Make sure your camera flash is turned on, preferable in "forced flash mode"
3 For best composition - get low, shoot at an upwards angle, don't center the subject, try to fill your frame with the subject. Down shoot "down" at the subject
4 Make sure the subject's eyes are in focus
5 Get your diving skills down before you start using a camera underwater
6 Practise topside with your camera inside the housing. Try taking close-ups of flowers and household objects
7 To minimize backscatter, buy an external strobe/flash and position it away from your underwater camera housing
8 Set your camera to the highest resolution, and the lowest ISO to begin with
9 Use auto white-balance when using a flash/strobe, and custom white balance or underwater mode when not using a flash
10 Learn how to use manual mode or aperture priority mode if your camera offers it, so you control the balance between the natural light and the light from your flash
11 If you are shooting with natural light, shoot in 20ft of water or less, with the sun behind you
12 For quickest focus, use spot focus mode. Learn how to focus on an area without taking a photo (pressing the shutter button halfway) and recomposing.
13 If your underwater photos don't look sharp, check to see which shutter speed was used, it should needs to be 1/30th for still objects, 1/60th for slow moving objects, and 1/125th of faster for faster moving fish.
14 Most underwater photos can use an increase in contrast when post-processing your photos - but don't overdo it.
Mistakes beginner photographers make
1 Use manual white balance every 5-10ft when shooting ambient light. Newbies often don't do this and end up with blue photos.
2 Taking photos with a lack of contrast; You should shoot in clear water, get closer, use strobes to light the subject. Use Photoshop to increase the contrast.
3 Taking photos with a lack of color; The solution is to shoot with strobes! block out ambient light with a fast shutter speed. Get closer. Make sure your settings are not letting in too much ambient light.
4 Lack of subject, or taking a photo that is cluttered without a clear subject. Solution – try CFWA or fill-the-frame techniques.
5 Lack of sharpness; See the section on getting sharp photos.
6 Too much backscatter; see the backscatter underwater section;
7 Shooting only in landscape mode; think portrait, shoot vertically 50% of the time
8 Don't shoot a subject more than 2-3ft away if possible; this is also called “shooting through too much water”
9 Having a distraction background. See the underwater composition section.
10 Thinking you can use a long zoom lens (e.g. - 18-200mm zoom underwater) – not a good idea. Either there won’t be a port long enough, or performance will suffer at the long or the short end.
11 Trying to shoot a busy reef in 1 photo. Try to isolate subjects on the reef, instead of creating a cluttered photo
12 Trying to shoot a fish 2 or 3ft away at F22, after shooting a nudibranch very close-up. It won't work, the subject will be very underexposed due to strobe falloff. Dial-down to a larger aperture, such as F7
13 Accidentally shooting at ISO1600 or at small jpeg quality the entire dive. Always check your ISO and JPEG/RAW quality before starting a dive, this should be part of your test-shot routine.
14 Oversaturating your photos. Many beginners pump up the saturation too much. Try increasing the saturation only 5-10% at most.
15 Not using the lens for what its for, and therefore trying to shoot through too much water.