Computer monitors produce millions of colors by
mixing varying levels of red, green, and blue light. These three
are complemented by opposite colors of cyan, magenta, and
The strobe's diffuser is used to reduce light intensity by 1-2 stops
in case your images are being burnt out. It also softens the light
and provides a smoother effect. I need to use a diffuser when
doing macro with my digital camera. It varies according to several
factors, especially film rating & subject distance. You should
shoot a test roll in a pool with a colorful fish-sized subject at
distances of 2,3,4 & 5 feet, one shot with and one without
diffuser to find the optimal combination before your trip. Do the
same with the macro kit (at the prescribed focusing distance) if you own
one. As long as you keep using the same ISO/ASA film speed you can
use your new settings without fail.
Remember that your photofinisher can also make-break the appearance
of your prints if they are not careful to properly expose underwater
prints that have large expanses of blue water in the background.
Automatic printers try to expose navy blue ocean to match sky blue; if
you are having this problem have them print it again manually, perhaps
take a magazine photo along to show them what the ocean's supposed to
look like to a diver. Check the prints before you leave the
counter. You should not have to pay for a re-do.
Many folks who thought their UW photos were bad just didn't get them