Lighting Guide To Underwater Wide Angle Photography
As the sunlight hits the water and filters through the depths of the ocean it gets absorbed, and therefore lost. You may remember the ROYGBIV acronym from physics class that abbreviates the colors of light in order of wavelength. This is also the order of the color of light that gets absorbed in the water column as you get deeper. That’s why so many underwater shots look so blue, as that is the color that gets absorbed last. Therefore, underwater photography requires external artificial light to restore the colors that are lost. For in-depth information on underwater lighting and using strobes, visit the underwater lighting guide.
Balancing Ambient Light and Strobe Light
Remember when shooting wide angle that your strobes are used exclusively to light your foreground subjects, while proper ambient exposure ensures a color-rich and crisp background. Your goal should always be to balance your light in such a way that both the foreground and background are well exposed and there is contrast and separation between them.
Always start by metering mid-water and setting your aperture and shutter speed to achieve a pleasing background exposure.
There are three types of exposure metering modes – Matrix or Evaluative metering, Center Weighted or Average metering, and Spot metering. Your camera defaults to Center Weighted / Average metering, which is a good starting point and a setting that you may choose to not change. However, different situations call for different metering methods, so you should aim to understand the difference between each. You can read more in our exposure metering guide.
Once you have a handle on creating proper background exposure, the next step then becomes easier, which is to vary your strobe power settings and positioning to properly exposure the foreground subject. Strobe power settings and positioning can make the difference between poor, drab or outstanding lighting in any particular image. Spend some time practicing this on a sponge, coral or other stationary subject.
Always be aware of the direction of the sun, changing weather conditions, and your depth. As one or all of these factors change, you will need to change your settings to achieve a good background exposure in the new conditions.
For example, if you are shooting towards the sun and achieve a good background exposure at f/11 and a high shutter speed like 1/160, a 90° turn away from the sun will change the level of light and exposure of your background by at least one or two stops. A 180° turn from the sun even more so. If you are shooting on a wall, the additional shade from the wall itself will possibly make the change even more extreme. Another example would be when the sky suddenly becomes more overcast. This could also result in at least a one to two stop difference in exposure of your background. Your choice in either case would be to first slow down the shutter speed from 1/160 to 1/125 or 1/90, or alternatively to open the aperture, maybe from f/11 to f/8 or f/5.6. The latter would result in a lower depth of field a bit, but wide angle lenses have a larger depth of field than macro lenses, so opening up the aperture a bit will not have as dramatic impact on depth of field. However, it is very important to note that while changing your aperture will affect your strobe lit foreground exposure, changing shutter speed will not. This is important if you are happy with your foreground exposure and only need to adjust your background. The reason for this is because the actual strobe duration is significantly faster than your shutter speed. Hence the recommendation to change shutter speed before aperture.
First, we should note that strobe positioning can make or break an image. Have an open mind – there are no rules, only starting points.
Generally, strobes should be positioned out to the sides and behind the plane of the camera to prevent the illumination of backscatter.
Angling your strobes away from the subject slightly outward will also help to reduce backscatter. Bracketing for strobe positioning is a really good idea.
Your LCD screen will be an invaluable resource in this process. Shoot at the standard starting position, and then move the strobes so that the light is hitting your subject from different angles. Notice the different quality of light from different angles.
Your strobe positioning will vary based on what you are shooting as well. A wide reef scene may require a wide even lighting approach, while shooting a diver looking at a large sponge formation, or an approaching shark may benefit from having one strobe act as the primary, or "key" light, while the second strobe acts as a fill light.
When using ultra wide lenses like fisheye lenses, you will want to be aware that flaring in your dome port is possible and pulling the strobes further back behind the plane of the camera will solve this issue. Sometimes pulling the strobes in towards the camera and pointing them slightly outward also helps.
Sometimes the best images are those that appear to have no strobe at all, where in actuality without the strobe the image would not have been possible. The image below appears to be lit by the sun, and for the most part it is, but without the strobes filling in the shadows and accentuating detail and color in the foreground, it would lack impact.