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Fibres
by
Colin Gray
Reproduced
from in focus 38 (October
1990)
I
have lost count of the number of problems that have occurred
with leads for underwater flashguns. 'Waterproof' leads
that leak. 'Wet' leads that can in theory be connected
and disconnected underwater have an annoying tendency to trigger
themselves with any slight movement.
Sooner
or later both types can fracture, repeated exposure to pressure
breaking the strands of the cable one by one until there is
an erratic fault either at the camera or flashgun end.
The
recent interest in TTL flash is likely to amplify the problem,
because of the extra wiring involved. 'Splashing out'
on a Motormarine II last season was, for me, initially a step
backwards. I have found no real advantage in the TTL system,
but it meant reverting not only to 'dry' leads,
which cannot be unplugged underwater, but also to only one
flashgun, with the strong shadows that such a system can produce.
I
do have a couple of small Ikelite flashguns, fitted with 'wet'
leads, that have slave sensors built-in. Now these things
are smashing for your buddy to hold so that you can take pictures
of your gun firing, but not very sensitive if trying to trigger
them yourself.
The
solution is, as usual, obvious once you see it. In our local
'Aladin's cave' of odds and ends I found a length
of fibre optic cable. With a bit of patience and quick setting
epoxy resin, I moulded a socket at the base of the 'master',
built-in, flashgun and another over the sensor of the 'slave',
remote, flashgun.
The
result is a tiny, waterproof, incompressible 'wet'
lead that can be replaced very cheaply and quickly when necessary.
It should even work if fracturedl The prototype cable has
now formed a couple of interesting right angles, but fires
the slave every time.
The
initial results have been very encouraging. Phase 2 has involved
installing a tiny flashgun inside my SLR housing to trigger
two slaves, although there is no limit to the number that
could be triggered this way.
A
slight 'technical hitch' occurred at this stage
. . at a depth of 20 metres the picture started to wobble!
Experts call these shots 'split image', but it is
not recommended to allow water inside the housing in order
to achieve them. Anyway, it was my lucky day and the water
did not penetrate the camera itself. The housing has now been
rebuilt and phase 2 is working perfectly.
Phase
3 - with the appropriate electronic circuits at each end,
there is no reason why even 'dedicated' flashguns
and cameras cannot communicate with each other down an optical
fibre. We might even have a TTL system driven by one lead
I
Postscript
The
Sea and Sea flashgun leaked after 11 month's use, probably
the cable as usual. It was returned as 'beyond repair',
so I have converted it into another slave, and am using the
Sea and Sea built-in flashgun to fire three guns!
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