I guess that AFO stands for “Automatic Flash Off” function, and it stops this happening.
I don’t know how it does it, but the Big Blue FF 4x5 AFO senses the camera’s underwater flash going off and extinguishes the constant light from the lamp before the camera sees the flash. That’s quick.
I couldn’t understand how it worked. After all, once the flash has fired, the picture has been recorded. But it seems that the Big Blue lamp operates faster than the speed of light.
Suffice to say that behind the camera one is left unaware that it is doing anything, because the Big Blue lamp comes alight again immediately after, but I can confirm that the tell-tale yellow spot left in pictures by other focusing lamps is absent. As I said, it’s magic.
The Big Blue lamp mounted conveniently on one of the ball-mounts of my camera housing. I was disappointed that it could not go on the ball-mount at the centre, for I found that its unusually long, pointy body tended to give me a headache every time I went to look through the viewfinder.
So I placed it on a ball-mount on the handle at one side and moved one of the flash-mounting arms over. Of course, there is the option of a conventional handle instead of the mounting ball for those who simply want to use the Big Blue as a diving lamp.
On my previous visit to dive Truk wrecks, I had taken the wrong sort of diving lamp, one with a very narrow beam. I had ended up needing to scan around engine-rooms to see what was there. Often, I got more information about my surroundings from my camera’s LCD screen after I had taken a photograph.
I promised myself that things would be different for my second visit and, thanks to the Big Blue lamp, they were.
The lamp is of anodised aluminium available in a choice of bright colours or conventional black, and measures around 22cm long and about 7cm in diameter. It weighs around 780g, including its batteries in the dive bag.

Light Source
A powerful 4x Cree chip sits behind an optical lens to punch all the 750 lumens of light forward. The beam produced is very even overall, but unusually it has a sharp edge to the arc of light it projects. This arc is said to be 44°.
It is also fairly cool-looking light, at around 6500°K colour temperature. The effect is that of a very sharply contrasting light.

Power Source
Eight AA batteries sit in a chassis and power the lamp. The rear part of the lamp unscrews to give access to them, and is protected by double O-rings.
The model is said to have a burntime of three hours on full power and five hours at its reduced power setting with fresh alkaline cells. You can opt to use 1.2V rechargeable cells.
As the reduced power setting is only 70% of full power, I had a hard job distinguishing which setting I was using. Let’s just say that both settings provided an unusually bright light, and one set of batteries was sufficient for all the time I spent in dark places over a week.
I didn’t do any night dives.

Switching
The AFO is switched on and off by rotating a plastic collar around the lamp, and this operates the magnetic switch. A thermal protection system ensures that the lamp does not get damaged should it be turned on when not submerged.
The light switches back on as soon as it has cooled sufficiently. A safety lock on the switch helps to reduce the chances of it being switched on inadvertently.

COMPARABLE LAMPS TO CONSIDER:
Light & Motion Sola 500D, £259

SPECS
PRICE £299
LIGHT SOURCE Single 4 Cree with optical lens
LIGHT OUTPUT 750 lumens
POWER SOURCE 8 AA batteries
BEAM ANGLE 44°
BURNTIME 3-5 hours
SWITCH Magnetic
DEPTH RATING 100m
CONTACT www.bigbluedivelights.com
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