Artificial Sunlight

Beams of sunlight stretch down from the surface and paint dancing highlights across the seabed, it is part of the essential ambience of the underwater world and a favourite component of underwater photographs. But we don’t get this light in all conditions. It is a rare treat.

The obvious requirement is sunshine, but equally important is a smooth water surface. It does not need to be millpond flat, but must be unruffled by the wind. Gentle waves, on the smooth surface, act like a series of lenses refracting the sunlight into focused beams, which in shallow water draw the classic pattern of flecks of light on the seabed. When the wind blows it rips at the surface creating lots of tiny wavelets, the surface no-longer can focus light into clear beams and instead we see blurry patches of light on the sea bed.

So one of the challenges for the underwater photographer working in shallow water is to find these conditions. Some places are blessed windless conditions, freshwater is often much more protected than the sea. In other places we can find patches of calm, such as shelter from high cliffs or a large dive boat, which can create a small area of perfect light.

The angle of the sun also changes the nature of the light. When it is overhead the beams will penetrate deepest into the water column in a tightly focus sunball. As the sun drops low in the sky, so the sunball is spread out, with the sunbeams refracted over several waves, creating rows of beams. Because the sun is at a low angle these beams do not penetrate as far into the water column, so to capture them at their best we must stay shallow.

The other difference between a high sun and low sun is the water colour. When the sun is high, midday in the tropics, light penetrates deeply and therefore the beams are set against the water at its brightest blue. When the sun is low, much of the light is reflected by the surface of the water and it is only the beams that penetrate, giving striking shafts of light against a dark water background. My friend and underwater photography guru Martin Edge famously called this “dappled light” and incorporated it in his images as often as possible. He regularly related the advice he was given years ago by Peter Scoones, which is well worth repeating, “When you have this light, find any subject you can to photograph against it”.

Underwater photographers regularly talk about time of day as the main control on the angle of the sun and people make a special effort to be in the water early in the morning or the last hour before sunset. On an overseas trip it is the only factor to consider. But for those who dive in more temperate zones such as here in the UK, season is also important. Winter months in the UK provide us with a chance to photograph dappled light all day. Providing the sun is out and we can find calm water. Our inland sites, in winter, are often perfect in this respect.

But we all know the sun doesn’t always shine, and this month I want to share some experiments I have been making to recreate some of the characteristics of underwater sunlight with a strobe. This month’s image was taken during the day, a cloudy day. I used a small aperture and fast shutter speed to remove all ambient light from the image, with a single Inon strobe on full power providing all the illumination. I had the strobe clamped on a long Ultralight arm and hoisted up out of water, pointed down on the subject. The aim was to produce the dancing light patterns of characteristic sunlight, but strikingly against a dark background, an impossible exposure if it was real sunlight. This technique requires both calm conditions and a slow moving subject close to the surface.

I accept that this is probably something of a love-it-or-hate-it photo; some of you will love it, others will think it a waste of a great subject. When we experiment we tend to produce images that show off the technique we are trying, with little subtlety. This idea probably needs some more refinement. I’d like to try the strobe at different angles and heights above the water – both pointing towards and away from the camera. I also hope some readers also give this type of lighting a try.

Finally, a word of warning if you do try this technique. Most underwater strobes are designed only for use when submerged. There is a risk of overheating if we fire them repeatedly out of the water. Please bear this mind, but we can’t push the boundaries of underwater photography without breaking a few rules!

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