Night & Photography: Because subjects at night are found at the end of your torch beam, they show their true colours. A light attached to your flash is best; and there is no better place to learn than in the sea at night, experimenting with colourful subjects and various angles of flash. Discipline yourself to work in a small area and get yourself a perfect buddy, one who not only acts as spotter, but leads the dive and so manages both your depths, dive times and direction. Certain species of coral and marine life retreat from any hint of light, and Edge views these with the very outside edge of his modelling light. His own particular night-time successes have been when working near the surface, where numerous creatures, including squid, lionfish and pufferfish, are, contrarily, attracted by moonlight or dive lights. Other good subjects are parrotfish, fish eyes, fish portraits and profiles, small marine life on corals and crabs. But don't waste time shooting what can be seen during the day.

Shipwrecks: They are usually deep. Use the widest angle lens you possess and available light, no flash. Martin used a 16mm full-frame fish-eye lens for this shot of the stern of the Giannis D in the northern Red Sea. The diver is equipped with a video light, so it will record on the film, and the subject has been positioned within the frame on the thirds intersection, being directed by hand signals. Use a faster film, like 200 or 400 ISO.

Divers: First rule, tell your model not to look directly at the camera. Instead, you should create the feeling that he or she is looking at something, and wherever possible, include the source of interest in the picture. Eye contact is important, so make sure the model (or your buddy's) mask has light in it, either flash or natural. Isolate the diver from a cluttered background by surrounding him or her with blue or green water - obtain a low viewpoint and shoot up into mid-water. Bubbles look good, so get the uman subject to exhale. And finally, you don't have to have a diver in the shot to fill space: the use of a model can sometimes ruin a great shot.