INTERESTING DIVELIGHTS

I've always had a flashlight fetish. "Light" was my first word,
and one Christmas my parents swear that all I wanted was a bunch
of colored lightbulbs and a lamp. I don't quite remember the
details (I was maybe four), but I'm told I managed to amuse
myself for hours with this, and not electrocute myself.

Well, not much has changed in 40 years. The other day I was at a
local REI store buying some underwear for the drysuit (I don't
care what you iceholefreaks say, the Pacific this time of year is
way cold enough for me), and I ran across a couple of neat
lights. Had to buy `em.

1) A Tec 40 divelight for $17. I'm always on the lookout for
lights which use AA cells, since by far the most excellent and
reasonably-priced disposable cell on the market is the red-top
Energizer AA lithium. The "Tec 40" uses 4 AA cells and is as
bright as you'll find in a 4-cell. With the much lighter lithiums
rather than alkalines, it's very nearly neutrally buoyant. Burn
time is five hours with alkalines, and would guess at least twice
that with lithiums. It's claimed to be watertight to 2000 ft,
though they didn't say if this was fresh or saltwater ;).
Probably below my MOD, anyway. I'll probably velcro mount it on
the top of the right hand with the head at the knuckles, caver-
style. The light is short enough to do this and still bend the
wrist. I'm really tired of the heavy divelights, and I'm NOT
going to buy a canisterlight until they finally come out with a
rechargeable lithium one for under $400. Which means not for a
while. Like I should live so long.

The flashlight company, "Princeton Tec" (www.princetontec.com)
makes a bunch of other divelights which are rigged to take
advantage of the nifty AA lithiums. There are two headmount
lights, which look like 4 and 8 cell lights. There is a 2000 ft
pressure rated "aquastrobe" which uses a single AA cell rather
than the single C-cell variety I paid a lot more for at my dive
shop. All homage to supporting local diveshops, but not when the
price factor is greater than 3. So check this company out.

2) A blue-white 2-LED light for $27. I'd just read about these in
Alert Diver, and By God, there one was at REI. This one is made
by C.Crane Co. (ccrane.com) and not sold as a dive light or
warranted to be pressure-resistant. However, neither is its
direct competitor, the "Trek 2" by Tec-tite mentioned in Alert
Diver. The 3-AA cell "CC Trek Lite" has the one-piece "twist-on"
gasketed design of a pressure resistant light, and is worth a try
as a dive light, I think (I'll report here after I try it). I
bought it mainly to play with the white LEDs, which I'd never
seen.

Well, they're white! Tide bleach commercial white. Blue-white
like Vega, colortemp 6200 K.* This 3-cell light has a burn time
of 50 hours (and puts out light for 100), and double these
numbers at least for lithiums. Again, with lithiums it's just
barely negatively buoyant in freshwater. "Bulb"-life (LED-life)
is supposed to be thousands of hours. You pay for all of this by
getting less than 10% of the light output of the halogen 4-cell.
However, the gentle white radiance is enough to examine a lot of
things underwater from a few feet away, and perhaps give them
some of their "true" sunlight colors also. This one makes a good
backup light, since it runs forever and you can hang it anywhere
on you, leave it on for the entire dive, never change batteries
in two days of diving (heck, you wouldn't even have to remember
to turn it off in that time), and otherwise forget it. And this
much light is infinitely better than none, if your primary craps
out on a night dive.

The Tek-tite company (www.tek-tite.com) mentioned by Alert Diver
supposedly makes a very cheap ($60) 7-LED light (using 3 C-cells)
which would be 3.5 times as powerful as the 2-LED version. If you
managed to find 3 standard carbon C-cells (she sells C-cells by
the seashore), and I wouldn't use the heavy alkaline in this
application because you don't need the life, then you can keep
the weight down. In this case probably close enough to neutral to
velcro one the underside of the left fore-arm, with the LEDs just
below the wrist and pointed slightly away from the arm. This
would make a nice "near-diffuse-illumination" setup for night
diving, while still using a conventional halogen beam on the
other arm/hand for a focused far-illuminator.

SBH

* Those of you who know about IR-fluorescence photography may
know about the problem of trying to do IR-fluorescence viewing in
realtime with an IR viewer. You need a bright, nearly IR free
light source, and this is very difficult to do with filters,
since there are no good ones which block near-IR well, and
conventional incandescent sources put out more IR than vis.
Portable fluorescents with green filters have been the best you
can do for this, but it looks like the white LED in theory is a
viable alternative for non-flash IR-fluorescence illumination. I
find on experiment that the white LED puts out very little IR,
and what's left can be dealt with easily with a standard green
filter. The problem is increasing power enough to see any IR
fluorescence with a standard IR viewer. Hmmm. I'm not sure I see
it. Perhaps another factor of 10 in source intensity...