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Close-up
and macro photography
by
Brian Pitkin
Reproduced
from in focus 17 (Aug.
1986)
A
standard lens such as a 50mm land lens in a housing or the
Nikonos 35 mm lens will allow photographs to be taken underwater
at a minimum distance setting of about three feet. With a
Nikonos 35 mm lens set at f22 this means that anything closer
than about 18' to the lens will be out of focus.
It
is possible to take sharp, in focus, photographs closer than
this using a wide-angle lens. However the resulting image
will be distorted, particularly at the edges of the picture.
To
obtain near distortion‑free images at closer distances
than can be achieved with a standard lens, underwater photographers
have a choice of two options, both of which involve changing
the characteristics of the lens system.
Firstly,
the primary lens can be changed for another with a shorter
focal length or its focal length may be altered by the addition
of an accessory or secondary lens. For the underwater photographer
with a housed camera, a macro lens such as a 55 mm macro lens
provides a very versatile means of getting closer to a subject
without losing the ability to take scenic shots with the same
lens. For the owner of an amphibious camera, however, there
is no alternative but to use a secondary or 'close‑up
lens'. Since this secondary lens can be removed underwater
if needed, the photographer can still use the primary lens
to take scenic shots.
Secondly,
the primary lens can be moved further from the film plane
by inserting a so‑called 'extension tube', which extends
the distance between the lens and film plane and thus allows
the lens to be brought very much closer to the subject. Unlike
close‑up lenses, however, extension tubes cannot be
removed underwater, at least not without flooding the camera!
Although
I have suggested that there are two options available it you
wish to get close, these options fullfill different needs.
These needs depend on what you wish to photograph.
A
standard lens such as the Nikonos 35 mm will cover an area
of about 90 times the area of a 35 mm transparency at a distance
of about three feet, Obviously, if you fit a close‑up
lens or extension tube to the primary lens, in order to get
closer to your subject, the area you will cover will be considerably
less. In fact the addition of a close‑up lens to a 35
mm lens will enable you to photograph an area of less than
half that of the 35 mm lens without a close‑up lens
attached. By comparison the addition of an extension tube
will limit you to an area of only three times the area of
a 35 mm transparency or less, depending on the length of the
extension tube.
CLOSE‑UP
LENSES
There
is an almost infinite range of lenses available for housed
land cameras, the 55 mm macro lets being the most popular
as it allows both close‑up and scenic photography. For
amphibious cameras, such a Nikonos, there are a smaller number
of accessory close‑up lenses available which can be
fitted onto the 35 mm, 28 mm or 80 mm lenses, and as I have
already mentioned these can be removed underwater should you
wish to take scenic or non close‑up shots.
One
of the difficulties of fitting a close‑up lens onto
the primary lens of a Nikonos is that the camera's parallax
viewfinder is totally useless for composing your picture.
In addition the depth of field is drastically reduced, so
that focusing becomes extremely critical. The problem of composition
may be partially solved by the use of a framing device or
probes, provided with all close‑up lenses. This also
overcomes the problem of focusing. The framing device or probes
only partially solve the problem of composition because your
eye can never be exactly in line with the lens. You do not
see exactly what the camera sees as you tend to be looking
down over the top of the camera at your framer and the subject.
With practice, however, this minor draw back can be taken
Into account.
Normally
the same close up lens can be used on either a 35 mm, 28 mm
or 80 mm lens. The focal distance will remain the sam, only
the area covered will differ. A close‑up lens on a 35
mm lens will cover a larger area than the same lens on a 80
mm lens and the same lens on a 28 mm lens will cover a larger
area than either an 80 mm or 35 mm. Normally framers or probes
are provided with your close‑up lens for use with two
or more different primary lenses.
Your
choice of close‑up lens will depend on how much you
want to spend and your reasons for taking photographs. The
Nikonos close‑up system is excellent, if somewhat overpriced.
The lens is clamped onto the outside of the primary lens and
additionally secured in place by a rod inserted in the hot
shoe of the camera body_. Since it is normally necessary to
flood the space between the close‑up lens and the primary
lens it is all too easy to lose this small rod, unless you
tie it on. The lens comes with three framers for the 35 mm,
28 mm and 80 mm lenses.
The
Ocean Optics close‑up lens is very similar in specifications
to the Nikonos close‑up lens, although considerably
cheaper and more compact. It is provided with a pair of probes
rather than a framer. The lens is clamped onto the outside
of the primary lens. The probes screw into the front of the
lens mount in one of two positions, depending on whether you
fit the lens onto a 35 mm or 28 mm primary lens.
Close‑up
lenses are also available for the Sea and Sea Motormarine
SE 35 mm camera and the Sea and Sea 110 Pocket marine. These
are screw on supplementary lenses with a single focusing probe
or wand. It is also possible to buy simple, cheap but effective,
lenses to screw onto Nikonos lenses, but you will need to
shoot a test film to determine the focal distance and make
up your own focusing rod to use these.
Whether
you choose a close‑up lens with a framer or with probes,
will depend on personal preference. Although probes are less
likely to cause shadow problems and are more versatile, they
may be, initially at least, more difficult to use for accurate
framing.
EXTENSION
TUBES
Extension
tubes fit between the camera body_and primary lens. Once fitted,
they cannot be removed underwater.
The
available tubes for Nikonos cameras reduce the lens‑to‑subject
distance to between 1 7/8 inches and 5 inches, so even in
very poor visibility you can still take reasonable photographs.
With such a small working distance, of course, the area covered
will be very small as compared to the standard lens on its
own. Tubes are described by the reproduction ratio that they
can achieve. At the upper end, a 1:3 extension tube, will
enable you to cover an area 3 times the size of a 35 mm transparency;
working up in magnification, a 1:2 extension tube will enable
you to take half life-size photographs; a 1:1 will allow you
to take life-size photographs; and a 2:1 extension tube will
allow you to take photographs at twice life-size. In practice
a 2:1 or 1:3 reproduction ratio is achieved by combining 1:2
and 1:1 extension tubes.
As
with close‑up lenses, there are problems of focusing
and framing when using extension tubes. These problems are
overcome in the same way, by the use of framers or probes.
Depth of field is greatly reduced, so your subjects must be
fairly flat if they are to be completely in focus.
Tubes
for the Nikonos are made by Oceanic, Ocean Optics and Sea
and Sea. The Oceanic and Ocean Optics tubes are made from
machined and anodised aluminium, whereas those made by Sea
and Sea are made from injection moulded plastic. The Oceanic
tubes come with a fixed metal framer. The framer supplied
with the Sea and Sea tubes has removable side probes. The
Ocean Optics tubes have a pair of probes. The latter are also
available in a vertical format version.
Prices
vary, the most expensive is not necessarily the best. Aluminium
has the advantage of being more robust, I have seen two cameras
flooded In succession whilst using the same moulded plastic
extension tube with an unnoticed hair line crack.
LIGHTING
Unless
you are extremely close to the surface you will need to use
artificial light in order to correctly expose your subject
and bring out the colour when taking close‑up or macro
shots. An electronic flashgun provides the easiest solution.
It does not need to be a very powerful flashgun, nor does
it need to cover a wide-angle. Provided the flashgun will
allow you to expose a subject at f16‑22 at a distance
of one foot, it will be perfectly adequate. If you have a
more powerful flashgun, you will probably need to either use
a diffuser or, if more than one power is available, use half,
quarter or one-eighth power, or move the flashgun further
from the subject. Too much light and you will overexpose your
subject!
Most
flashguns are provided with an arm and tray. Although these
limit possibilities when taking non close‑up and macro
photographs, unless you detach the flashgun from the tray
and hand hold it, they can be quite useful when taking close-up
or macro shots. Aim to position the flashgun so that it evenly
illuminates the area within your framer. Slightly to the left
and above the camera is usually fine. Although some macro
set ups position the flashgun just above the camera's centre,
this may flatten the resulting image by totalling eliminating
shadows. Once you are used to your system, try moving the
flashgun to one side or behind the subject. Balanced light
shots are also possible with close‑up. Don't be afraid
to experiment, you may be pleasantly surprised with your results.
FILM
If
you are taking close‑ups or macro photographs you will
need a fine grain film to capture the fine detail. Kodachrome
64 and 25 are probably the best choice of transparency films,
but Ektachrome 100, Agfachrome 50 and Fujichrome 50 and 100
are very strong contenders.
SUMMARY
Whether
you use close‑up lenses or extension tubes there can
be no easier way of taking successful, underwater photographs.
Assuming you have run a test film and
a)
know the correct setting for a particular colour
subject and
b)
preset the focal length of your primary lens, following the
directions for using your close up lens or extension tube
(either closest distance or infinity), then every picture
you take should be In focus and correctly exposed.
All
you need worry about is finding subjects and composing your
shots! |
