What is the angle at which the lamp is opened?

The angle of opening of the lamp beam can be defined in a simplified way as: the width of the light where most of the lamp's illumination will be concentrated, about 80%-90%.

This value tells us the angle at which the light beam opens, and therefore determines the area it can illuminate depending on the distance to the light source. We must bear in mind that LEDs are more focused than halogens, for example, and therefore we should pay particular attention to this aspect.

Depending on its intended use, we will be interested in a light source with a specific opening angle. Typically, lights with a narrower opening angle are used as accent lighting, to highlight decorative elements or, in a shop, various products. Conversely, lamps with a wider opening angle, usually 90 degrees, are used for general space lighting.

The amount of light that a lamp will provide in a particular application will not depend solely on whether it has a higher number of lumens; there are also other factors that affect it, such as the angle at which the lamp beam opens.

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The amount of light in an airplane is directly proportional to the luminous flux or number of lumens and inversely proportional to the angle of the light source. That is, the higher the lumens of the light source, the brighter the perceived light in a given space; however, the wider the angle of the light source, the less bright the perceived light in that space.

In the following example, we will try to explain it visually:

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We can see how an 8-watt lamp with only 800 lumens, when used in this application, gives us a greater sense of brightness (lux), because it lights up in the direction we want thanks to its 180-degree opening.

The other lamp has a greater amount of lumens but, on the contrary, has a 360-degree opening that wastes the light illuminating the ceiling, and therefore, in the area that concerns us, it gives a much less glare-like feeling.

To choose one angle over another, we must consider the height of the lamp and the surface to be illuminated. If the height is high and the angle is very wide, we will lose light intensity compared to more focused light, but the illumination will be more even. Conversely, to illuminate a room with a low ceiling, if we use a light fixture that dims the light considerably, we can create shadow areas where the illuminated areas will be clearly defined, as if we were using a flashlight.