Underwater photography can be some of the most challenging—and some of the most rewarding. Nature photography on land is difficult enough, given the fact that you have to consider accurate focus, a myriad of light situations, creatures in constant motion, and finding the most natural and pleasing color balance.
With digital photography, the camera's sensor has a lot of latitude to see light—but certainly not like our own eyes. That is why the final image often does not even resemble what you actually see. The first and most noticeable reason for this in underwater photography is light loss. Unlike land photography, where morning and evening provide the most pleasing light, underwater photography (with wide angle lenses) is best attempted during bright mid-day light. Why? It’s just a fact of life that light has a more difficult time penetrating the density of water.
Also see: Underwater Strobes at Adorama
Water is 800 times denser than air. With this lack of light, underwater images often take on a monotone blue hue and have very little contrast. Add particulate floating in the water, and it makes it that much harder. If you have been diving, then you understand why you may carry a torch/flashlight even during the day. At depth, the colors of the reef just don’t show up. Here is an example of light loss using a color chart at varying depths.
Think the colors of the rainbow, then start subtracting:
Yes, this chart was in The Top 10 Fundamentals of Underwater Photography but it doesn’t hurt to look at it again!
Note that even when snorkeling in very shallow water (15 feet) the first color to diminish is red – and quite frankly, most reefs have animals that are brilliant red, orange, and that entire spectrum. Frequencies of ambient light get absorbed beginning with the longest wavelength (red) to the shortest (blue). So it makes sense that the deeper you go the next color to diminish is orange, followed by green, then finally, blue.
Fiji Islands Reef top in 15 feet of water shows diminishing color spectrum.
Colors in same reef are restored with strobe lighting.
Color is even affected by the distance between your lens and subject. Horizontal lighting is no less critical than vertical. The moral of this story is to get close—really close! The water between you and the subject can also affect contrast and saturation. There is nothing worse than having that whale fill the frame only to find your image is muddy and that you really don’t recognize it as a whale.
From a horizontal perspective, the strobes can light area close to the light source but as the distance increases, colors begin to mute. It’s called light fall-off. Lens: 16-35mm
The weather and surface conditions can also impact the lighting situation. I prefer a beautiful bright sunny day and a glassy water surface, but that's not always an option. Any cloudy day will obviously reduce exposure just as in any topside situation. Throw in the density of the water, refraction and other elements, and a wonderful underwater landscape cannot be captured with any color or contrast. Now add a choppy sea. How easily does the available sunlight penetrate the water? Not very well when the light is bouncing off one wave of water to the next before it even has a chance to penetrate the surface!
At eighty feet in depth, these schooling fish at left have lost their color under ambient light in the shot at left. Right: Artificial light in underwater photography adds the wonderful colors back into the subject. Lens: 15mm fisheye
How about refraction? Good grief! Something else to impact the quality of your underwater photos!!!
Technically, refraction is the directional change of a wavelength of light due to a change in its speed when passing from one medium to another. Water has a refractive index of about 1.33. For this reason, the fish that is staring you in the face will appear about 25% bigger and closer than it actually is. I like Matt’s way of demonstrating: Place a pencil halfway in a glass of water. The pencil will appear to bend at the water’s surface due to the bending of light rays as they move from the water to the air. Got it now?
That brings us to backscatter. Remember that I mentioned the word particulate? Sometimes it’s as tiny as a grain of sand, which is just as annoying. However, when that particulate turns into chunkage, it’s time for the macro lens. One of the hazards of using artificial lighting underwater is that the particulate can light up and look like it’s a winter blizzard outside, even if the palm trees are gently waving above the surface and the water temperature is warm and soothing. We’ll talk more in depth about how to avoid this another time.
This shot was taken in only 15 feet of water. My strobes did not fire so you can see the lack of color in the piers. Lens was a 15mm fisheye.
Add the strobes back in, and you can see the difference in providing artificial light.
So remember these three factors that can affect your image:
- Subject Distance
- Weather/Surface Conditions.