Today we will study colours and how depth and underwater conditions affect light and photographs. Even on the sunniest and clearest day, 50% of brightness is lost in the top metre of water:
- The first reason is that part of the sun’s rays hits the surface and is reflected.
- The second reason is that the sun’s rays change their angle when passing through water.
- The third reason is that when light passes through water, the beam is absorbed and scattered.
These three characteristics of light manifest themselves on the calmest days — add a few waves, and you will have even less available light. Waves kick up sand and other foreign particles, blocking the light. That is why, even if you decide to descend to a depth of just 20 metres during waves, you already need at least a canister diving torch.
Have you noticed how colours change when diving to different depths? But did you know that red disappears at a depth of less than 5 metres? Following our rainbow colours, orange disappears at a distance of about 8 metres, yellow at 10, green at 20, and finally, blue is absorbed at a distance of about 60 feet.
Due to reflection, refraction, diffusion, and absorption, we do not have much light to work with when we scuba dive. That is why the use of diving torches, as well as video lights and strobes, is important for photography — light sources add the missing colours back into the visible spectrum and allow us to see the underwater world as it really is.
However, to buy an underwater torch from an online shop is only half the battle; the light must be used correctly to achieve the best result. The type of light source, the number of sources, the placement, and the proximity to the object should be taken into account.
Let’s start with the distance to the subject
The light source for your photos obeys the same laws of physics as the sun’s rays, so you need to position yourself as close as possible to the object, while not disturbing the animal you are photographing. If you are too far away, the light will refract and scatter, and the colours will be weak as it diffuses.
Another reason to get closer is to eliminate as many objects floating in the water between the camera and the fish as possible; specks of sand and other particles will reflect light and scatter it. Even if you didn’t know this, you have seen this effect in photos — tiny dots everywhere that ruin an excellent shot.
What light to use besides a torch? A strobe or a video light?
The main difference lies in the output power — a strobe can be five times brighter than a video light and captures fast movement better. As for the positive side of a video light, you can illuminate the subject and shoot in burst mode, while your friend with a strobe, having taken one photo, waits for it to recharge. A video light can also show you exactly what your image will look like in the viewfinder. Both types of light sources have their pros and cons.
If you are a fan of macro photography, you can bring one strobe to catch a fast little creature. If you are more attracted to wide-angle landscape shots, choose two strobes. But if you prefer video to still shots, purchase a dedicated video light. Remember that the best part of underwater photography is experimenting with the equipment. With experience, you will find out what works best for the types of photos you want to take.
With any lighting setup, check the exposure at different depths and adjust it if necessary. If you set up the camera in the deepest part of your dive, these parameters will most likely turn out to be too high when you ascend a little higher to the surface and photograph a fish hiding under the boat.