What are Beam Angle and Field Angle in Lighting?

What are Beam Angle and Field Angle?

The beam angle is a very important technical parameter for LED lighting. It is one of the technical parameters that describe the effective area illuminated by the lamp and plays an important role in the quality and effect of the light.

According to the standards of the CIE International Commission on Illumination, The angle through the center of the beam where the light level has fallen to 50 percent of the beam’s maximum brightness is called the beam angle, and the unit is °.

From the definition of the beam angle, it can be concluded that part of the light emitted by the entire lamp is not included in the range of the beam angle. The angle through the center of the beam where the light level has fallen to 10 percent of the beam’s maximum brightness is called the field angle, and the unit is also °.

In summary, the beam angle measures a source's intensity until it has fallen 50%. The field angle measures the angle of a source's intensity until it has fallen 10%. Their relationship is shown in the following figure.

Common Beam angles in LED lighting

In practice, different beam angles have their own purposes. Different types of LED lamps typically have different beam angles. For details, please refer to the table below:

When should you choose a narrow beam angle?

Narrow beam angles range from 5 to 45 degrees. They produce concentrated and intense light that can highlight fine details or create dramatic contrasts. They are ideal choices for high ceilings or long distances, as light needs to travel further and reach specific areas. They are also applicable to highlight lighting or task lighting, where the focus is on specific objects or activities. However, if used improperly, narrow beam angles can also produce dazzling shadows, glare, or uneven lighting.

A narrow beam angle is a great choice for centralized lighting, which can illuminate the surface and highlight finer details in the space. For example, in a kitchen you should opt for a narrow beam angle over all task areas such as the benches and dining tables. This will provide sufficient lighting for your surface to complete tasks like preparing meals, cooking and cleaning.

When should you use a wide beam angle?

Wide beam angles range from 80 to 130 degrees. They produce diffuse and soft light that can cover a large area and create a uniform effect. They are ideal choices for low ceilings or short distances, as light does not need to travel far and can spread evenly. They are also suitable for environmental lighting or general lighting, with the aim of creating a comfortable and pleasant atmosphere. However, if used improperly, a wide beam angle can also lead to light pollution, energy waste, or reduced contrast.

Lounge rooms are a perfect space for wider beam angles, as you don’t need the area to be as bright. A wider beam angle distributes light to more areas of the room, making it the perfect choice for spaces that require light to flood that area but not as intense.