Everyone wants to make his UW Images more striking – and one of the most popular ways to achieve strong images is to present the subject on a black background. And even though it is possible to achieve this effect in Photoshop or other editing programs, it is much easier and faster to do so straight when you take the shot. The basic principle to achieve a black background is to eliminate ambient light and only illuminate the subject with the strobes.
How to eliminate Ambient light: First choose the shortest possible shutter speed – this would be 1/200th or 1/250th with most DSLRs. Second choose a relatively small Aperture: f16 or a higher number. This makes sure no ambient light will be visible on your exposure. This depends a lot on the amount of sunlight and the depth. Also you will have to stop down more if you are shooting towards the sun. The best way to test if you setting are sufficient is to switch off your strobes and do a test shot: The result should be a completely black screen.
How to only light the subject: There are two ways to achieve this – either you look for freeswimming or exposed subjects or you have to be creative with your strobe positioning.
Easy to subjects are either subjects swimming in the water column like Anthias or other fish or subjects sitting well exposed like shrimps or gobies on whip corals or subjects sitting on edges.
If the subjects are on the bottom or well exposed but close to a background like a reef, the beam of light from the strobe must be directed so that he illuminates the subject but not the background. This can be a harsh downlight in between subject and port for close to the bottom subjects or a harsh sideways light for subjects in front of backgrounds. Another way is to look for a better angle that makes achieving the black background easier.
After having realized how easy it is to do black backgrounds you might also want to try blue or other colours … just to keep your portfolio a little bit more diverse. Because if all Photos have a black background they don’t stand out anymore 😉
