| Generally, the word "bracketing"
refers to exposing one or more darker and/or lighter frames
of the same subject after taking a frame at the exposure value
suggested by the camera’s metering system and after
taking one at your "best guess." If you are shooting
"TTL" with a Nikonos V, you will reset the ISO dial
for a higher number to darken your frame to a lower ISO to
lighten. If your are shooting "TTL" with a single-lens
reflex camera, this is done by adjusting the exposure compensation
dial "+" for a lighter or "-" for a darker
image. If you are shooting manual you will close your aperture,
turn down power on the strobe, or move the strobe back to
darken; or you’ll open the f stop, move the strobe in,
or increase strobe power to lighten a subsequent exposure.
I believe that it is best to think of bracketing as a tool-not
a rule. Bracketing is a form of insurance. It buys you some
confidence that you’ll have an overall properly exposed
photograph—but at a cost. The cost is paid in time and
film. You might think of bracketing in the context of its
purpose. You are trying to come up with as many good—hopefully,
excellent photos as you can on a given dive. If you have one
camera with thirty-six frames, you’re on a shallow dive
in Fiji with maybe an hour or an hour and a half of air in
your tank, you’re up to your eyeballs in mind-blowing
subjects that your slide files are just crying out for and
you’ve been getting fairly consistently good results
exposure-wise lately, you may wish to submit to your natural
greedy nature and forego bracketing in favor of the prospect
of a major jackpot. If it’s a once-in-a-lifetime subject,
you may want to cover your nudi-branch, or whatever, with
a couple of judiciously taken brackets.
If you have just landed in the middle of an underwater wasteland,
you may have to make the most of anything you can find. Since
a lot of time will be spent on finding your next subject,
and film is not a limiting factor, make absolutely certain
that you fully exploit the photographic opportunity at hand
by bracketing not only exposure, but camera angle, light balance
and direction; and if the subject is moving, you can do it
all again when the subject changes position. Bottom line;
you are maximizing your take of images; and bracketing is
one means to that end. Even on a dive in paradise, with subjects
everywhere, you may have a once-in-a-lifetime image in your
finder, and you’ll bracket the shot any way you can
think of! You buy all the insurance you can get—you
spend all your film and all your bottom time.
Some subjects lend themselves to bracketing more than others.
Sedentary subjects such as coral, are easy to bracket and
contrasting colors may simply look better at one exposure
than another. Subjects with IQs measured in less than several
decimal points require more selective timing for the desired
image to appear ideally on film. Then photographing fish,
you may be waiting for a subject to position itself near a
certain background, face a specific direction, raise a dorsal
fin, make eye contact, etc., etc. Odds are that everything
won’t stay right for you to bracket the same exact shot,
especially after your 150-megaton strobe just exploded in
his kisser. For this reason, make your first exposure as right
as possible, and don’t rely on bracketing to yield one
good frame out of three or more. If you are using TTL correctly,
or have your guide numbers down and are judging distances
well, your first shot will usually be either best or close
enough to make a near-perfect dupe or print.
Having said all this, it must be noted that for many subjects,
there may be more than only one "correct" exposure.
Some images look better on the dark side, some lighter. Two
photographers may disagree in their judgment as to which of
two different exposures of the same subject looks best. Bracketing
allows you to choose the best exposure at your leisure. It’s
a simple percentage game. When you think that saving your
time and film for other subjects will yield the great pictures
on a given dive—bracket less. When you’ve got
a good subject and you don’t want to gamble on finding
a better one—bracket more. Lady Luck and Cousin Murphy
will have the final word any way you decide to go!
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