What is luminous intensity? It is the unit of luminous intensity, used to measure the luminous ability of a light source in a specific direction. For example, the luminous intensity of car high beams is usually more than tens of thousands of candelas, which can illuminate the road ahead at a long distance, while the luminous intensity of ordinary flashlights may only be a few hundred candelas. Applications: In road lighting design, it is necessary to reasonably set the luminous intensity of street lamps according to factors such as road grade and traffic flow to ensure that the road has sufficient brightness and uniformity. In stage lighting design, lamps with different luminous intensities are also used to create various lighting effects according to the needs of the performance.What is illuminance?
Illuminance (lux, lx) refers to the brightness when light hits an object. It represents the luminous flux per unit area and affects the perception of an object’s brightness.
- Under moonlight: 0.3 lx (barely visible)
- Ordinary home lighting: 100-300 lx
- Close-range direct light from a strong flashlight: tens of thousands of lx
The farther the light source is from the object, the faster the illuminance decreases. A flashlight appears dimmer from a distance than up close precisely because the illuminance becomes lower. What is color rendering index? Color rendering refers to the ability of light to truly restore colors. CRI (Color Rendering Index) is a measure of a light source’s ability to reproduce the true colors of objects, with a maximum score of 100.
- CRI of 90 or higher: High color rendering, with natural and true colors (such as in photography and medical scenarios).
- CRI of 80-90: Sufficient for daily use.
- CRI below 70: The colors of objects will be significantly distorted, which is common in low-quality cold-light flashlights.
Some high-brightness flashlights have high brightness but poor color rendering, making things look gray. If you need to look at maps, plants, wounds, or colored objects, it is recommended to choose a flashlight with high color rendering.
What is color temperature? Color temperature is a definition in illumination optics, a physical quantity describing the color of a light source. Simply put, it refers to the luminous color, and can also be understood as the visual perception that light gives you. Its unit is “Kelvin” (often denoted by the symbol “K”). The lower the K value, the warmer the light color; the higher the K value, the cooler the light color, showing a gradient from red – orange – red – yellow – white – blue – white.
What is a lumen? Definition: It is the unit of luminous flux, used to describe the total amount of light emitted by a light source. For example, a 40-watt ordinary incandescent light bulb has a luminous flux of approximately 340 lumens; while an LED bulb of the same power may have a luminous flux of more than 4000 lumens, which means the LED bulb can emit more light. When choosing lighting fixtures, the lumen value is an important indicator to measure the brightness of the fixture. For example, in the lighting design of a living room, depending on the size of the living room, it is generally necessary to choose fixtures with a total luminous flux of about 1500-3000 lumens to provide sufficient brightness. However, a high lumen value does not mean the light can reach far; how the light is distributed is the key. If the light spreads out completely, the distance will be dark, which involves “luminous intensity”.