What is a “beam angle”?
In simple terms, it is the width of the light emitted from the luminaire, measured in degrees.
A common misconception is that the area outside the stated beam angle would be “dark,” however, this is not the case with common residential lighting. Useable light will still fall outside the stated beam angle.
This is important to understand when choosing beam angles. Wide beam angles are not “better” than narrow beam angles. There are applications
that simply require one or the other.
Modern LED’s can produce light in a relatively wide dispersion pattern, but the direction of LED light can be controlled more efficiently than traditional lighting technologies. LED light from narrower beam products is controlled by secondary lenses in front of the chip.
IES files contain beam angle information that is used by lighting designers to help create the effect you are looking for.
Advice: Beam angle choices can be subjective and used to advantage for great lighting effects. Experiment to see what works in your home. For commercial environments, engaging a lighting designer will ensure Australian Standards are met.
Beam Angle Definition
The beam angle of a flood style light bulb lets you know how much area it will illuminate at a given distance (beam spot size). The lighting industry has developed a uniform formula to determine the beam angle. The light output (lumens) is measured at the center of the beam and then light strength (intensity) is measure out from the center until it is 50% of the intensity level (as measured in the center). The beam angle is then determined in degrees (see below). The most common designations for flood light beams are Spot (7 to 15 degree), Flood (20 to 30 degrees) and Wide Flood (35 plus degrees).
The beam angle does not tell all the story. It is impotant to know that the light continues to spread out into what is called the Beam Field. The Beam Field is the area the light covers that has at least 10% of the maximun beam intensity (see below diagram). The lighting industry does not test for the Beam Field but a good rule of thumb is to double the beam angle.
The Beam Angle that the manufacturers provide as a degree does not help most people. What you want to know is the area that a flood light will illuminate. The spot size of a flood light bulb is the diameter (at any given distance) that the bulb illuminates to 50% of the maximum light output. The below calculator will help you to figure spot size. You need to know the distance to the area or object being lit and beam angle of the light bulb. Fill in the distance and the beam angle boxes. The calculator can be used with any standard of measurement (inches, feet, meters, etc). Click on the calculate Spot Size button to get your answer.
What are the different beam angle types?
Beam angle of various spots light.
The beam angle is expressed in degrees, indicated by the sign '°' or 'D'. The most common beam angles are 24°, 36° and 40°. The right choice in the beam angle depends on the purpose you have with the light.
Beam angle 10°
The small beam angle. Commonly used when you want to ‘highlight’ something, putting it right in the ‘spotlight’ like art.
Beam angle 24° - 40°
The medium beam angle gives you a wide light. This one is the most commonly used and most of the time placed in places like retail, restaurants and in houses.
Beam angle >60°
The wide beam angle. They have a very wide beam angle, and are mostly used in places with large surfaces like warehouses and offices.
Since there are quite a few different beam angles some manufacturers have decided to simplify it a little bit. Beam spread is identified by putting them into one of the three groups: narrow, medium, and wide.
Very Narrow Spot
Very Wide Flood
The importance of beam angles in lighting
As the resident, in-house lighting designer here at Shine On, I thought it necessary to share the importance of light beam angles when looking to upgrade the lights in your property, or when installing in a new build. Maybe it’s something you have never thought of, but if you select the wrong light and your beam angle is out, then you will get lower than ideal light levels and poor uniformity. This in a nutshell means bright and not so bright areas in your space.
How you measure a beam angle
The light’s beam angle is the angle from peak light intensity to where it drops off to 50% of that peak. For most fittings, the maximum light is directly below the luminaire and the light then disperses out until it hits 50% of its peak. Everything below 50% is called spill light and the total angle of light distribution from peak to no light is called the field angle.
A graphic representation of a light’s beam angle is depicted in the illustration below.
Why do beam angles matter?
Controlling the light distribution and getting the light where you want it is just as important as how much light you generate. The main things that affect the beam angle are the height of the ceiling the fittings are mounted to and the spacing between the fittings.
One important part of my job is to ensure that we put the right fitting for the height of the ceiling and that they are spaced appropriately. This ensures that there is no spill light and the beam angles overlap so there is always 100% illumination on the workplane.
In general, in order to get uniform lighting:
the higher the mounting height, the narrower the beam; and
the wider the spacing, the wider the beam.
How you can change the beam angle
Beam angles are particularly relevant to high ceilings in industrial spaces which often have highbay lights. The easiest way to change the beam angle in this situation is to use a reflector which can disperse the light more or less depending on the height of the ceiling or the space between lights. This is why it is so important to have adaptable lights like our H-Flux Mk3 highbay which has five interchangeable reflectors for almost every situation. Other LED highbays, such as the UFO, don’t have changeable beam angles and therefore aren’t flexible for non-standard spaces.
You can also change a lens on a chip itself usually used in floodlighting to alter the beam angle.
When looking to upgrade your existing lighting to LED or if you’re building from scratch, make sure you employ an experienced lighting designer at the start of the process. If you have any need, please contact us at email: firstname.lastname@example.org