I AM REGULARLY asked for my tops tips for underwater photography. As with any question, the answer always changes a little, depending on who is doing the asking.
If it is for a general-interest piece for a newspaper, the answers will be more straightforward. If it is a friend who is already an accomplished shooter, my reply will be tailored to his or her level.
That said, a couple of points dominate all replies. First is to continually develop your diving skills.
Few things will improve your underwater images as quickly as really good in-water abilities. And be sure to practise these skills while holding a camera.
I regularly meet new photographers who are confident that their buoyancy and trim are spot-on. But often it all comes crashing down when they put a camera in their hand.
Carrying something changes their carefully configured system. As Peter Scoones used to say, if you want something done under water ask a photographer, as everyone else is good only at floating about!
Diving skills help with so many aspects of shooting. It is easier to make a stealthy approach, it is easier to accurately frame a subject and, because you are holding the camera still, it is even easier for the autofocus to lock on.
As a stable diver you will cause less intrusion and will be rewarded with regular displays of natural behaviour. You will stir up less sediment and get clearer pictures, and will not accidentally cause damage to delicate marine life.
Finally, it is valuable to remember that this is not a binary division. We are not divided into good divers and bad divers. Instead it is a sliding scale, one up which we can all endeavour to progress.

AFTER TELLING people to work on their in-water skills, the second most important tip for successful underwater photography is to get close, then get closer. This is because the biggest problem of making images under water is the water itself. So the closer we get, the less of it we shoot through and the fewer problems we have.
This is why the right lenses are critical under water, and why it is worth spending more on a wide-angle lens than a fancy camera. The most useful lenses for underwater photography will always be close-focusing macro and ultra-wide-angle lenses.
However, where is the fun in photography if we’re not prepared to bend or even break the odd rule? The grandest stories we can tell under water are painted on the biggest canvases.
This month I want to encourage you to try shooting with your widest lenses, but not from as close as possible to the subject. Instead, back away to between about 75cm to a maximum of 1.5m.
In standard photography terms this is still close-up work, but in underwater terms this is far away.
The first requirement for big-scene shooting is good underwater visibility, and this is not a technique for murky conditions. The next choice is strobes or filter. Both have their merits and challenges. and it is a decision we make before the dive.

BIG-SCENE SHOOTING with strobes is a serious lighting challenge, which is less about finesse and more about getting light and colour on the subject without generating backscatter.
Strobes need to be out on our long arms and also pulled back so that the fronts of the strobes are in line with the handles of the housing. Pull them back too far and you waste power; let them creep forward and scatter really strikes.
Our strobes should be aimed pointing forward, not angled in, out, up or down. We don’t want to waste light going in the wrong direction. Both strobes can be set to the same high power.
It is impossible to light big scenes without picking out some particles in the water, but we want to minimise backscatter. Backscatter can be hard to see on a small LCD screen, so after shooting a few shots of big-scene wide-angle, I will zoom in on the sides of the frame and check.
Scatter will always be worst at the edges, but check both sides because one strobe may be set slightly differently, and it takes only one to ruin things.
A few speckles are unavoidable, but if the backscatter is a big distraction push the strobe out wider and pull it further back.
The other challenge is getting enough strobe light to the subject to avoid leaving it too blue. Normally we would simply turn it up. However, in big-scene shooting we are often already maxed out, especially under the tropical sun.
The solution is to open up the aperture and speed up the shutter-speed by the same amount, increasing the ratio of strobe to ambient light. Changing ISO is no help in this situation.

FILTERS ARE THE alternative way to shoot large scenes in colour, but are limited to subject matter at depths shallower than 15m.
Filters are also fitted for the whole dive, so you need to know ahead of time that there is appropriate subject matter at the appropriate depth.
The golden rule with filters is to work with the light. The sun is our only light source and we must take as much care positioning it as we do with strobes. We can’t move the sun, obviously, but we can move ourselves and ensure that we approach the subject from the correct direction.
If we shoot across or against the sun, the subject becomes partly silhouetted and colour and detail are lost. Success comes from shooting religiously with the light.
Once we get our aim right, light and colour take care of themselves, leaving us to concentrate on composition.
This is one of the biggest challenges of shooting big scenes, because busy pictures are messy pictures.
When working with a big canvas, take your time to get all the elements pleasingly arranged.

STARTER TIP
Underwater cameras are at their largest when shooting big scenes with strobes. Long strobe-arms are essential to avoid backscatter in these shots, but a big rig is also a big drag to push through the water, especially with buoyancy foam on the strobe arms.
Unless you fancy a work-out, favour current-free dives on which the plan is to avoid lots of swimming.

MID-WATER TIP
Shooting from a distance can leave your subject slightly off-colour. As long as you get some strobe on the subject, you can usually correct this cyan colourcast with a quick white-balance adjustment in post-processing.
Try clicking on the subject with the white-balance dropper and then just slightly backing off the correction for a subtler result.

ADVANCED TIP
A downside of having a big canvas is that it is hard to fill well. The riot of life on coral reefs is rarely organised into pleasing graphic shapes, which is why close-focus wide-angle images dominate in contests. This means that concentrating on producing an attractive composition is essential for success.