The Camera (Canon 350D)
Take your pick I'm not biased, I have a Canon
350D, which is one of the early "cheap" Digital
Single Lens Reflex (DSLR). It does not have a
full size (35mm) sensor but a 26mm sensor so
called "APS-C". While not having the
performance of a truly top end camera it has
99.9% of the benefits for a third of the cost,
however, the APS C sensor does effect lenses
(see below).
While obvious, as this is a SLR the screen
does NOT show what you are photographing
like a point and shoot, you have to use the
viewfinder to compose and read your light
levels. (N.B. This has now changed on newer
DSLR's with live view but this does have some
lag and restrictions so jury is still out as to the
real benefit of this.)
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The Housing (Ikelite eTTL)
The housing needs to match the camera body, they
are either thick plastic or cast metal to match the
shape of the housing. Controls are worked via a
combination of sealed buttons and levers. There is a
window for the LCD('s) and a small lens for the view
finder.
If your housing is clear you can see any leaks,
hopefully in time to do something, if it is metal it is
common to have a leak alarm which will give an
indication.
Different housings also have different depth ratings so
if you breath Trimix pick your housing carefully (my
Ikelite is NOT suitable).
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The Lenses (Sigma 10-20, Sigma 17-70,
Sigma 105 macro)
What do you want to photograph ? The key to
under water photography is keeping lens to
subject distance to minimum, to help this you
need the right lens for the job. If you want wide
angle wrecks and vista's then you need wide
angle, 10mm or so, if you want little Nudibranch
and fish faces you'll need a macro. Also
remember that if you have an APS C camera
you will get a "crop" factor of 1.6 which means a
105mm is more like a 170mm lens.
10-20mm : Wide angle, wrecks, reefs, and
close focus wide angle.
105mm Macro : With a +4 dioptre this will give
truly double life size on image sensor. I.e. if you
photograph a 10mm Nudibranch on an APS-C
camera it will be 20mm big on a 26mm sensor
so fill the frame.
17-70mm : This is not great for either option but
is a good "scout" lens and ideal for first dive to
have a look see and decided what is down
there fore second dive. This lens also has 1:1
macro so not as good as a pure Macro it does
give some ability.
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The Port (Ikelite 6" dome, Ikelite 8" dome, Ikelite Flat
Macro.)
The port is the bit that goes on the front of the housing
to enclose the lens. These don't include come with the
housing and you have to get one that will match the
lens or lenses you have. Dome ports are essential for
wide angle and the bigger the radius the better. For
macro flat is better as the refraction effect on the front
pane will give further magnification.
It is important to be sure your lenses will fit your port /
housing both physically and optically, manufacturers
have charts to help.
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The Strobe (2 pcs Ikelite DS-125)
Whilst the key to underwater photos is lens to
subject distance the second has to be light. In
order to replace the light lost through the water
you need a flash, or strobe as they are called
underwater. I'm of the school of thought that
thinks more light is better, you can always dial it
back, so I have two strobes but one will work
fine. When selecting strobes need to consider
the power output, re-cycle time (time to
recharge between flashes) and triggering
system.
They will need to be triggered in some form
from the camera / housing either by cable (with
or without exposure control (5A)) or optically. So
you'll also need a cable (or two) to connect the
strobe connector on the housing to Strobe way
out on the end of the arms (6).
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eTTL
In order to control the amount of light the strobe gives
you have two options, manual (via power controller on
strobe) or automatically with TTL. TTL is an old
protocol (from NikonV time) which was standard,
however, due to the advent of digital and the
complexity of there flash system there are now
multiple protocols, all of which need an interface. As I
use canon I need eTTL which is combined into my
Ikelite housing, however you can also buy third party
converters.
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The Arms (Ikelite)
In order to avoid back scatter (from having the
light source and the lenses pointing in same
direction at the subject) you need to have the
strobes offset from the camera. To do this you
need "arms",
There are various types and are
interchangeable to some extent, however check.
I have Ikelite; Left side quick disconnect 14" (so
I can hand hold easily); Right Side, 1x4" and
1x6" with articulated ball joints.
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