| There’s absolutely no doubt that
autofocus is a useful tool underwater—in some circumstances
more that others. For fish photography, it’s generally
quicker and more accurate than even the sharpest-eyed underwater
photographer attempting to focus manually. Autofocus, however,
is a poor substitute for being able to see. Most wide-angle
and macro shots are generally better handled by manually focusing.
It’s also important to consider that fact this if your
vision is letting you down in the focusing department, you’re
probably working under some kind of handicap when it comes
to composing, too. It seems that by the time we reach a point
in our lives when we can afford to buy the kind of camera
we always wanted, we can’t see through it anymore—sort
of a corollary of the old axiom that "youth is wasted
on the young." At about the same time, it gets harder
to read those gauges and find subjects on the reef. I’ve
been there and done that!
Let’s take a look at the more general problem that
focusing is just a part of. We’ll assume that your visual
challenge is one of accommodating (ability to focus the eye)
and not in the clarity of the lens of your eye. If you’re
wearing prescription glasses out of the water, you have a
correction for astigmatism, accommodation, or for both. You
can solve your underwater vision problems, including focusing
your camera’s lens, if you wear corrections underwater.
You could wear glasses inside your mask, wear contacts, or
have corrective lenses installed in your mask. If bifocals
solve your problem on land, then may be the way to solve them
underwater.
If you have lenses ground for installation in your mask,
the normal procedure is to grind in the correction for any
astigmatism and to accommodate the mask for infinity. If you’re
satisfied with your ability to meet any visual requirements
in your diving with your mask corrected this way and have
just found a problem focusing your camera, you can place a
lens between your camera finder and the viewing port of your
housing. An easy way to do this is to take your mask and camera
to your local major drug store and go to the rack of ready-made
reading glasses. Put your mask on (be certain that everyone
knows that you don’t have a gun) and start placing different
reading glasses between your mask and camera finder. You’ll
almost certainly find one pair that affords just about perfect
vision for focusing. Buy this pair and simply pop the lens
out and affix it to the back of your viewfinder before you
close the housing. You’ll be good as reborn! If, however,
you’d like to have better close vision, you feel lucky,
and you decide you want it all, you may want to take a different
approach in correcting your mask.
I want a completely unimpaired view through my camera viewfinder,
and since most people look directly through the top third
of the mask, positioning a bifocal line in the mask is problematic.
This may not be a problem for you, as many people claim to
do quite well with bifocal masks. However, when looking through
a camera viewfinder, the eye must be able to accommodate at
about three feet, since this is the equivalent distance at
which the focusing screen appears sharp. So I figure that
if I’m focused at three feet by my mask, then I can
see perfectly through my camera, I can see my gauges fine,
and I can find enough of the little kelpie-looking critters
in the kelp and sea-fanny-looking creatures in the sea fans
to keep me cheerfully occupied.
I explained this new insight to my optometrist and requested
that he give me a prescription for my vision a three feet
for installation in my mask. Reluctant at first, he asked
me how I planned to find the boat. Somewhat annoyed that he
would think I hadn’t thought the thing through, I explained
that I planned to go to the surface and swim in ever-increasing
circles until I bumped into it. He was obviously impressed
with my thoroughness and gave me the prescription. I think
the system works great. Actually I’m only very slightly
impaired at distance as anyone would be if they still had
the slightest ability to accommodate. If you’re not
comfortable with this solution, you might stay with the lens
in your housing, an infinity prescription in your mask, and
a close-up lens glued to the outside of your mask low on the
lens so you can squint through it to see your gauges.
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