Spot beam

Also called pencil beam, long range beam, driving beam, spot pattern

A spot beam is a narrow off-road light pattern, typically under about ten degrees wide, that trades width for distance, and it is the only pattern with a good reason to be mounted high.

What is a spot beam?

The same light concentrated into a tight cone. Because intensity in a direction is what sets reach, narrowing the beam raises the candela at the centre without adding a single lumen, and a good spot reaches several hundred metres where a flood of identical output reaches fifty.

What you give up is everything either side of that cone. A spot on its own is a bright tunnel with darkness around it, which is disorienting and hides anything about to enter the trail. Spots are meant to be run alongside a wider pattern, not instead of one.

Why spots are the exception on height

Because a narrow beam lights very little air, and what it does light is a thin column that stays clear of your line of sight until it is a long way in front of you. That is the whole reason a spot can go on an A-pillar or a roofline when a flood cannot.

Baja Designs say this in their own guidance and give glare reduction as the reason: lights in their high-speed spot zone benefit from being placed higher, because the tighter beam negates what would otherwise be a concern of glare coming back into the cab. Their LP9 range makes the point inside one product, where the Pro and the Racer Edition share a housing, share the emitters, differ only in lens, and are specified for low mounting and high mounting respectively.

It is the narrowness of the beam that buys the height, not the height that improves the beam.

When a spot is the wrong lamp

At walking pace on rocks, where it lights a spot on a tree forty metres away and nothing you are about to drive over. In fog and dust, where reach is not the limitation and any additional light in the air is a cost. And on any vehicle where it is the only auxiliary lamp fitted.