Beam Angle: Fact & Fiction


Okay, I’ll say it…super-tight, light sabre beams are a hang-up of the past! Why… because older and less efficient technology (such as HID) didn’t have the light output (or lumens) to do the job. If you focused this light down to the tightest beam possible, it appeared brighter and had a chance in limited visibility or longer range signalling. Today, with the latest in LED and lithium battery technology, we’re able to deliver a light solution that is good for diving, and not just impressing divers in the car park.

Through trial and error, we’ve found that as we increased the lumen output we reached a point of diminishing returns with narrower beam angles. Quite simply, even in clear water we were unable to see as far as the light projects. With variable output, high lumen solutions, we believe a slightly wider beam (<10° in water) to be more practical for most divers.

FACT: Beam angle is the entire output of a beam, not just the centre spot

Be sure what you’re getting with a super-tight beam. Our beams are 6° & 8.25 ° for the LD-15 and LD-35 heads respectively. We believe these to be near optimum beam widths for the lumen output of these two different light heads.

FACT: Beam angle in-air is different to beam angle in-water

I’ll say that again, beam angle in-air is different to beam angle in-water. In fact, beams projected through a flat lens (as is the case with most dive lights) will be approximately 33% tighter due to refraction.

FACT: Light spillage is bad, and is unintended light escaping from an optic or reflector

Our beams have a full spot, with very little light spillage. We consider beam angle as the edge-to-edge distance of the beam, not just the center spot. Watch out when you hear beam angle quoted as “the centre spot only”, as you might be getting more than you’re bargaining for in terms of light spillage.

FICTION: Only super-tight beams can be used in limited visibility

Remember what I said earlier about “diminished returns” and higher lumen output? In limited visibility, if you can lower the lumen output of your beam, you’ll reduce the flare/backscatter you’re seeing; making your light more effective. All of our primary lights let you chose high, medium or low lumen output on the fly, at the touch of a button.

FICTION: Higher wattage means a better beam

Wattage is the measure of power consumption. Luminance is a measure of light output. The higher your lumens and the lower your wattage, the more efficient your light, and thus the longer it will burn for a given battery size. Don’t let manufacturers confuse you here, high wattage without lumens to back it up is a waste of battery.

FICTION: Our lights are dangerous for newer divers

I threw this one in for a laugh, though it is an example of the rubbish going around on some forums. On a serious note, get the right beam angle for your diving. Our LD-35 is the most popular choice because of its “Mac Daddy” lumen output and all round useful 8.25° beam (e.g. cave, wreck & reef). The LD-15 has smaller 6 ° beam and lower price tag, but packs a mighty punch for its size and is a favourite with serious cave and wreck guys.

Be informed, pick the right beam for the right reasons…