Does The Higher Lumen Make The Flashlight Brighter

People often ask whether the higher the lumen of a flashlight, the more the flashlight? How many lumens is bright for a flashlight? And is more lumens better flashlight?

Yes, there is a proportional relationship between lumen and brightness, if all other factors are the same. But lumen is not the only determinant of brightness.

Lumen

Lumen (Lm) is a unit of luminous flux and refers to the light output measurement. The greater the light flux of the light source, the more light is emitted.

1 lumens = luminous flux emitted by a point light source with a luminous intensity of 1 candela within a unit solid angle.

Brightness

Brightness is how "bright" a small area looks (perceived by the human eye). To say that a flashlight is "bright" does not mean that the flashlight has high brightness, because the flashlight has no concept of brightness.

The "brightness" that we usually perceive should be called "illumination". Illumination is the luminous flux received by the surface of the illuminated object per unit area. Someone call it luminous intensity.

1 lux = 1 lumens of luminous flux evenly distributed over an area of ​​1 square meter

The relationship between illumination and lumens is:

Lux = Luminous Flux / Illuminated Area.

Then we can have a very intuitive understanding now, the luminous flux (lumens) is a three-dimensional concept, and the illuminance is for a plane. At the same lumen, that is, under the same light flow, the illuminance value brought by the different irradiation areas is also different. The larger the radiation divergence area, the lower the illuminance. Vice versa, the more focused the light source, the higher the illumination on the focused area, because it sacrifices the illumination on the unfocused area.

From the above figure, we can also intuitively see that the brightness at different illumination angles (irradiated area) is different under the same lumen value. For example, a 900lumens flashlight, you will get a different brightness when you use flood lens instead of spot lens.

With the above theoretical basis, we can know that the same lumen of the camp light and the headlight, because the light diverges differently, the illuminance of the specific location is different.

The light of the camp light spreads evenly around, suitable for close-range lighting and camp activities. The headlights produce a focused beam of light. The illumination in the focused area is high, and the unfocused area can almost be said to give up lighting.

Some people say that my headlight has a very high lumen. Why can't I see anything in the fog?

Well, this involves the issue of light transmission. Different types of light have different penetration rates. Simple examples have the highest penetration of red light, so red lights are used to indicate stop in traffic lights.

Therefore, brightness depends not only on the luminous flux of the light source, but also on the equivalent light emitting area and the degree of convergence of the emission. To make the illuminated spot look brighter, we must not only increase the luminous flux, but also increase the means of convergence, which is actually reducing the area, so as to obtain greater intensity. This also solves such doubts, why the lumen of his flashlight is not as high as mine, but it is brighter than mine.