Ever wonder why the one light in a space makes such a tidy pool of illumination, but another appears to spread its light out over most of a wall? In many situations, the culprit is the beam angle. This parameter indicates how large the primary cone of output light is for a given fixture. With a narrow beam, all of the output light is concentrated on a smaller surface. But with a wider beam angle, that same output light gets spread out over a wider surface. Neither is always a better option. The right choice depends on what you want the light to hit, the distance from the light to its target, and the amount of contrast you feel comfortable having in a space.
A narrow beam may help draw attention to a painting, a bookcase, a textural wall, or even a little decorative accent piece. Because the light gets concentrated on just a small area, it may seem much brighter in the center of the pool of light than around the edges of that light. That creates the possibility for a strong focal point but also the likelihood for a harshly defined bright area or areas of shadow between fixtures. The effect of a narrow beam becomes most obvious at low mounting heights, where the beam is striking a surface that’s just a few feet from the light source. They’re good when you want to make a spot on a surface stand out in its own little area of lighting, but not necessarily for more general background illumination.
A wider beam helps to distribute the light on surfaces like floors and walls and work areas. The result is that you don’t get as many isolated bright spots. It also means you have more leeway for how to space out your fixtures so they don’t overlap with one another, as all the same lumens get used to light up a much wider surface area. The effect can look less intense but less harsh. Wider beams can be ideal when you want general lighting that falls from above, when you’re trying to light up a wall without a lot of glare, and in more compact spaces where several of those narrow pools of light may result in a mottled look of light and shadow. Remember, too, that surfaces matter. Lighter walls and more matte (less shiny) surfaces can make a room look more lit up, as light bounces off of them and gets spread out into the room again.
Another important aspect to remember when thinking of beam angles is how the distance between the light and the surface it’s shining on will make a big impact. For example, as you move the light further away from a surface, that cone of light is spread out over a much larger area. You can expect that light’s ability to be seen on that surface will be reduced because the lumens are spread out so much more. Move it much closer and you get a more concentrated light that is brighter. So, a fixture that has just the right beam angle for a high mounted ceiling may feel too narrow when used as a light that’s closer to an object under a shelf. Or, a light that’s a lot wider in its beam angle will feel less intense when placed too far back from an area you want to work at. While you can often see the beam angle info on fixture diagrams and spec sheets, it is often helpful to do a quick demo with a couple of different beam angles to really see the effect.
To do your own test on beam angles, place a light that moves around in front of a wall or surface you want to light and mark out where the edge of the light is with some pieces of removable tape. Take note of how bright the center appears to be, as well as around the edges, and where shadows from objects are landing. Then move the same light away from that same area and note what changes with how far the light is placed from the surface. Next change the angle of the light but don’t change its distance from the surface. If you can, try that with two different kinds of lighting. Snap a picture for both of them from the same vantage point. Try to keep all variables equal except for what you’re trying to show with these demonstrations so you know whether you’re seeing what the difference in beam is doing or something else.
Be aware that there may be an effect of a light on the quality of shadows in its space. The smaller and more narrow a focused light is, the sharper the edges on its shadows. The bigger, more diffuse and broader a light is, the softer the shadow transitions appear in that light. For task lighting, for example, the effect of that sharp shadow on a surface can block some of the light from a narrow beam being positioned just behind your shoulder or head. Whereas for accent lighting, a sharp shadow created by light being grazed across a textured wall can actually emphasize a design detail. So, take time to look at what’s going on with the shadows in that space from where you are seated at a desk or standing up at a work area where you want to see light on the surface, and from the viewpoint of others in the room as well; you could create a light that looks fine in a floor plan but is in fact directing light right into someone’s eyes.
Before choosing beam angle, take a moment to imagine where the light of a fixture would fall on a room. Think about how that light would land on a surface or space that you want to illuminate. Think about how that would meet up with other lighting from fixtures nearby to ensure there isn’t too much or too little light. Think about where the light is landing to make sure there isn’t a problem of someone getting direct light in their eyes. You want a light that works as much as possible for the space. This doesn’t necessarily mean it must be brighter, but that you have placed light where it would benefit the use of that room and let the shadow fall where it wouldn’t be problematic.