| Most zoom lenses generally considered
for use underwater are intended to serve slightly wide-angle
to short telephoto duties. A wide side of twenty-eight or
fewer millimeters requires a dome port. The telephoto end
of a 28-80 zoom behind a dome won't give you a bigger image
than a sixty behind a flat port (which actually magnifies
about 25 percent), so you get no help from the zoom in bringing
in small, distant subjects. Most zooms don't yield magnifications
greater than about 1:3.5 or so. If a film frame is one-by-one-and-a-half
inches, then the macro on the zoom will fill the frame horizontally
with a subject a little better than five inches long - okay
for some subjects but not most of the small stuff. A 105 micro
(micro = macro) will give you up to 1:1, allowing you to fill
the frame with a one-by-one-and-a-half inch subject area.
These "longer" macro lenses have longer working
(camera-to-subject) distance than their shorter counterparts.
Whereas the sixty will yield a 1:2 magnification at a working
distance of ten inches from the film plane in air, the 105
produces the same magnification at fifteen inches, an increase
in working distance of 50 percent. A 200mm macro will give
you the same half-life-size image on film at twenty-six inches
from the film plane in air, an increase over the 105 of a
little over 70 percent. Since there is only about a two-inch
increase in lens length between the sixty and the 105, and
between the 105 and the 200, the differences in actual distances
between the front of the port and the subject are substantially
greater underwater. Taking refraction of the flat port into
account, your 1:2 subject is a little over six inches from
the end of the port with the sixty, almost ten inches with
the 105 (an increase of about 66 percent), and twenty-three
inches with the 200, for an increase of 130 percent over the
105 and 400 percent over the sixty. The relative difference
in port-to-subject distances with these lenses at a 1:1 magnification
is even more dramatic.
It is interesting to see that problems in achieving a desired
result in underwater photography have the same solutions as
most other problems -- spending time and/or money. The 105
costs almost twice as much as the sixty, and the 200 costs
more than twice as much as the 105. If you can take the time
to learn the skills needed to move in on shy subjects and
the time during the dive to slowly and carefully approach
a subject, you can do it with the less expensive lens - with
a very nice side benefit. Since you're closer, and are therefore
shooting and lighting through less water, you'll get a sharper
image with better color. What this boils down to is that a
given photographer possessing a given degree of stealthmanship
might be able, for the sake of argument, to fill the frame
with a fire goby using a sixty macro in one to three dives
of about sixty-minute durations, get the same frame with a
105 in no more than one dive, or make the same frame with
a 200 micro in about three to five minutes.
All critters have a comfort zone - a distance at which they
will just tolerate a stranger. That distance is generally
longer for intruders making rapid motions, bubbles, or a lot
of eye contact. The distance usually shrinks with time, as
the subject starts to give you the benefit of the doubt on
such matters as how fast you can move, how interested you
are in him personally, and whether he's on your diet. Certainly,
some species are tougher to approach than others, and individual
members of a species vary in spookiness, as an individual
might from time to time. I had long been aware of that fact
when a yellow-headed jawfish in Fiji brought this awareness
to a new level. On this particular dive, I had chosen to take
the $1,300-three-to-five-minute approach to getting the shot
I was after and had dialed in the focus on my 200mm ED Micro
so that his eyeballs were sharp. I had just parked in front
of his property, and he was kind of swimming up to what he
considered a safe distance to check me out, then swimming
a few feet away, picking up and moving a little sand, and,
in general, trying to appear as nonchalant about me as I was
pretending to be about him. Then he swam back to the edge
of his comfort zone to take another good look at me. He did
this several times, and each time he reached the magic distance,
his eyes were at their sharpest in my finder. The fish is
about three inches long and filled about 80 percent of the
height of my frame when his eyes were sharp. Focusing is wide
open at f4. The distance on the lens at this magnification
is a little over two and a half feet and the depth of field
is virtually nil. Could this particular jawfish's comfort
zone be two and a half feet plus or minus absolutely nothing?
Could be!
So back to that fire goby. His comfort zone is real, definite,
and inviolable. He's drawn a line in the sand and said, "Cross
it buster, and I'll pop down into my hole so fast you'll think
I was a stinking hallucination! What to do? In all cases,
you owe it to yourself to appear as non-threatening as possible.
Most fish will accept you at a closer distance than they will
tolerate your bubbles. It's often helpful to get a handhold
on a rock or some other non-living structure and gently push
yourself back to breathe. Movement should be slow and fluid.
Don't maintain eye contact. Be sure that your gear isn't banging
or dragging on the bottom. Some photographers swear by camouflage
wet suits and camera gear to make them less obtrusive to their
subjects. These principles apply whether you're determined
to use the sixty to fill the frame with that goby at the shortest
working distance possible for the sharpest image obtainable
-- even if it takes the whole dive -- or if you're going to
use the 200 and fill the frame with that goby, two of his
neighbors, three jawfish, four different blennies, five species
of hawkfish, six brands of nudibranchs, and a partridgefish
in a pear seafan -- on that same dive. You fill your book
a lot faster using the 105 for small subjects and the 200
for the really squirrely ones. You can go back and get them
again with the shorter focal length as time and opportunity
permit. The fact is that in reasonably good water, with proper
lighting technique, you will get excellent images with the
200 macro on magnifications of 1:2 or 3.
Check this out: If you were to poll all of the wary creatures
we try to photograph, they would overwhelmingly vote for bubbles
as the single most disturbing thing about divers. If you were
to poll all the divers trying to photograph these same wary
critters, they would just as certainly agree that bottom time
is the single most limiting factor in getting those photographs.
Well, get ready for some great news! We are at the threshold
of the first revolution in diving technology since the dive
computer. This is an exciting time for divers --and especially
for under-water photographers. Enter the closed circuit scuba
unit -- the "rebreather." Many of us will soon be
rebreathing our carbon-dioxide-purged, oxygen-replenished
exhaled air. Zero - count em, zero - bubbles, markedly extended
safe bottom time when properly used. And it's finally here
- again! As there was with the dive computer, there is certain
to be some spirited dialogue as to the wisdom of the sport
diving public accepting this technology; however, these units
have been in use in commercial and military diving since before
the invention of Cousteau's Aqualung, our beloved bubble machines.
Could you use a couple more hours bottom time a day? Could
be! And all it will cost is money! Somewhere between the cost
of three to twelve 200mm macro lenses -- a lot of money. But
then, so do the better dive trips. Using the longer focal
length lenses will net you many more, much better photographs.
It won't be "Geez, I'd love to fill the frame with one
of those fire gobies" -- you'll get to where you won't
want to waste the frame if his dorsal isn't up. With your
rebreather, you might have twice as much time underwater on
every dive trip. Money can't buy happiness? Isn't a perfectly
framed, technically perfect shot of that fire goby happiness?
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