Flashlights, lumens and candela
Lumens and candela are two units of measurement used to describe the amount of light emitted by a source. While they may seem similar, they actually measure different aspects of light and are used in different contexts.
Lumens, often shortened to “lm,” measure the total amount of visible light emitted by a source. This includes all the different colors of light, as well as any infrared or ultraviolet radiation that may be present. The lumen is the standard unit of measurement for determining the brightness of a light bulb or other light source. For example, a typical 60-watt incandescent light bulb produces around 800 lumens of light.
Candela, on the other hand, measures the intensity of light in a specific direction. This unit is often used to describe the brightness of a flashlight or spotlight, as it takes into account the fact that these types of lights emit more light in one direction than in others. For example, a spotlight with a candela rating of 1000 cd would be much brighter in the direction it is pointed than a light bulb with a lumen rating of 1000 lm.
It’s important to note that candela is a measurement of light intensity and not total light output, so a light source with a high candela rating may not necessarily be as bright overall as one with a lower rating but a wider beam spread.
In general, when looking to purchase a new light source, it’s important to consider both the lumen and candela ratings. For general lighting in a room, you’ll want to look for a high lumen rating to ensure the space is well-lit. For task lighting, such as a desk lamp or reading light, a high candela rating may be more important to ensure the light is focused where you need it.
Another important concept related to light measurement is color temperature, measured in Kelvin (K). It’s a way to describe the color of a light source, with lower numbers indicating warmer, more yellow light and higher numbers indicating cooler, more blue light. This can be important to consider when choosing light sources for different settings, as different color temperatures can have different effects on mood and visual perception.
In conclusion, lumens and candela are two important units of measurement used to describe the amount of light emitted by a source. Lumens measure the total amount of visible light, while candela measures the intensity of light in a specific direction. Understanding the difference between these units and how they are used can help you make informed decisions when choosing lighting for different settings.