Chasing the Blues Away
By Marty Snyderman
In this month's question, Chester S. from Nashville, Tennessee, asks, "What can I do to get rid of the blues? In my photographs, everything including divers, reefs, water, fish and anything that should look red or orange is too blue."
Chester's problem is one that is faced by all underwater photographers every time we take a camera into the water. The reason is that water-whether salty, fresh, tropical, temperate, polar, clear or dirty-is a selective filter of the sun's light. Roughly speaking, the sun casts off equal amounts of red, green and blue light waves, the blend of which results in what we call sunlight, or white light.
However, the various wavelengths of light do not penetrate into the water column equally because water functions as a continuous filter. The deeper you dive, the broader the band of colors that is filtered out by the water column. Waves from the red end of the spectrum are filtered out first, while blue light penetrates the deepest. So while light waves that give us reds, oranges and yellows are being filtered out by the water, waves from the blue end of the spectrum begin to dominate the deeper we go, and as a result our photographs look bluer.
The best way for Chester to "get rid of the blues" is to use a strobe and get very close to his subjects. Strobes not only provide light for exposure, but they also "paint" lost, or filtered-out, colors back into underwater photographs. Strobe manufacturers go to a lot of trouble to produce strobes that emit light that is very close to white light with near equal amounts of red, blue and green waves. But water is also filtering light that is put out by strobes. If you are too far away from your subject, by the time the light travels from your strobe to your subject and back to your film, any light that strikes your film will have a bluish cast. Light from the red end of the spectrum would have been filtered out. When using a strobe you should never be farther than eight feet away from your subject and in most situations, the closer, the better.
If you have a photographic question for Marty, please send it to mar firstname.lastname@example.org. If your question is selected, the answer will appear in a future issue of Skin Diver.