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LAMP GreenForce Impact 100 HID
Brutish his demonstration might have been, but it was probably the most exciting thing that happened at this years SITA British diving trade-show held in Chelsea FCs stadium. I bet chairman Ken Bates, up in his office, was irritated by the sound! I know everyone else was.
It seems that while HID (High Intensity Discharge) lamps can deliver extra brightness, many were arriving back with their distributors like so many homing pigeons. They were proving too fragile in the rigorous world of divers.
GreenForce believes its Impact HID is the answer. Its products are made with anodised aluminium but two extra chemical treatments give them a hard, green-looking protective coating.
Each component is part of a system that allows the user the freedom to assemble it in the way that suits him best. You can screw any one of seven different lampheads directly into a selection of nickel-metal hydride battery packs, or opt for an umbilical cable and mount the battery pack on your tank or elsewhere.
Connections are protected by three in-line O-rings. A selection of different handles is available, so one mans GreenForce lamp looks very different from the next. You can also choose between a six-hour fast charger and a normal 12-hour charger.
The Impact 100 HID is a lot bigger than any of the other lampheads, so I opted to use the umbilical connection and mount the fat G1 Ni-Mh battery pack on my tank by means of a Lumb Bros pony clamp and mounting bracket, removing the battery pack handle so that there was no danger of snagging. A Lumb band and No 2 snap hook attachment was used to clip the lamphead conveniently to a D-ring on my BC. The lampheads large size did not prove to be a problem under water.
An HID lamp gives out a great deal of light for its size and voltage, and of a higher colour temperature than conventional tungsten lamps, which burn at between 2700ÃK and 3300ÃK.
Daylight is 5500ÃK but the GreenForce appears to burn at 6200ÃK, rather cold and unsympathetic to the things it illuminates. However, the higher the colour temperature or the bluer the light, the further it penetrates in water.
An HID lamp needs time to warm up, which precludes switching it on and off - lucky in this case, as there is no switch. You simply screw in the plug connection until contact is made.
Thats fine for turning on but I wouldnt trust a lot of divers to turn it off this way while under water, because it could be unscrewed too far and flood the unit. Its best to leave it on.
Ni-Mh batteries can be topped up at any time without damage, but they do give off gas, so I was pleased to see that a gas-vent valve was included in the design of the battery pack. Burntime for a fully charged unit with the G1 battery pack is certainly more than the 50 minutes I enjoyed on each dive.
The reflector unscrews to adjust the beam-width, protected by three O-rings in line. Again there is a risk that the heavy-handed could flood the unit by unscrewing it too far, so I suggest pre-adjusting it to suit your taste and leaving it set.
I found that the beam could be adjusted to make it fairly even, though not enough for use as a video light. The unit sent for test had evidently already been in far less sympathetic hands than mine and looked quite shabby even before I started.
However, it continued to work despite being bounced around the deck of various speeding small boats and in luggage loaded on and off numerous planes during an extended trip in the Pacific.
The GreenForce Impact 100 HID as tested costs577. The Lumb pony bracket is40 and the Lumb No2 snap hook attachment15 extra.
  • Lumb Bros 01616 815790, www.lumb-bros-das.co.uk


  • Divernet Divernet
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    + A simple robust system
    + Plenty of permutations



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    - Vulnerable to flooding in careless hands