What about the parameters of flashlight?

Luminous flux F (unit: lumen, i.e. lm)

It refers to the amount of light emitted by the light source in unit time and describes the total amount of light emitted by the light source. Generally speaking, if the wick is placed in a closed sphere and then lit, the overall light energy received by the inner surface of the sphere is the luminous flux of the wick. For outdoor headlights and flashlights, there is a positive proportion between lumen and brightness: the greater the lumen value, the greater the luminous flux, and the stronger the luminous capacity of the light source.

Power in Watts (W)

The power of the flashlight is no different from that of other electrical appliances. Power refers to the work done by an object in unit time, that is, power is a physical quantity describing the speed of work. The amount of work is fixed. The shorter the time, the greater the power value. Generally speaking, the power of the flashlight refers to the power of the flashlight light source, not the overall power. Under the condition of constant light efficiency, the power determines the brightness between different models of flashlight LED light source. However, the light efficiency of general LED is different, so it is not certain that the one with high power will be brighter.

Beam distance/range (unit: m)

The range of the flashlight will vary in different environments. Generally, it refers to the distance from the light source when the light emitted by the illuminant reaches 0.25lux (0.25lux, which is roughly equivalent to the distance that people feel in this field when the light emitted by the full moon in a clear night in an open field.)

Waterproof grade:

IPX is an internationally accepted waterproof level certification system. It is used to mark the waterproof level of the product on many outdoor, diving and other instruments and equipment, and is the most common technical indicator. The IPX waterproof grade is divided into 8 grades, from IPX-1 to IPX-8, and the waterproof capacity is enhanced in turn. The IPX8, the highest level, has the waterproof ability of no water ingress for 2 meters and 30 minutes underwater.

Battery capacity (unit: mAh)

The charge of ordinary lithium batteries and rechargeable batteries is milliampere hours, which is defined as the current generated by complete discharge within a certain discharge time. For example, 1300 mAh means that the battery can be fully discharged for 1 hour when the discharge current is 1300 mAh.

When we buy a flashlight, we always see 18,650, 21,700, 26,650 and other batteries used. What do these numbers represent after all? These five digits are actually the identification method of lithium battery cells for industrial use. The first two digits indicate the diameter of the battery, the third and fourth digits indicate the height of the battery in millimeters, and the last digit indicates the shape of the battery.

Take 21700 lithium-ion battery as an example: 21 refers to the external diameter of the battery is 21mm; 70 means the height of the battery is 70 mm; 0 means that the battery is cylindrical. With the same material, the capacity ratio of the 21700 battery is 35% higher than that of the classic 18650 cylindrical lithium-ion battery, and the capacity of the 26650 battery is about twice that of the 21700 battery.

Drop test:

The drop test is mainly used to simulate the free fall that the flashlight may be subjected to during use, and to investigate the ability of the flashlight to resist accidental impact. Generally, the drop height is based on the product weight and the possible drop probability as the reference standard. The drop surface should be a smooth, hard and rigid surface made of concrete or steel. For handheld products (such as mobile phones and MP3 players), most of the drop heights range from 100cm to 150cm. The severity of the test depends on the drop height, drop times and drop direction.

Color temperature of light source (unit: K)

To put it simply, color temperature is the temperature of light color. The lower the color temperature, the warmer the light color; The higher the color temperature, the cooler the light color. The light colors widely used in flashlights mainly include white light, yellow light, blue light and red light.

White light, also known as cold light, is the most widely used light color in the current flashlight series. The white light is close to the sunlight, which is also the most comfortable light color for the eyes. White light is higher than other light colors in terms of brightness and color temperature, giving the strongest bright feeling. It is suitable for long-distance lighting. Therefore, white light is widely used in outdoor activities such as night hiking and camp lighting.

Yellow light has the strongest penetrability. Under the same conditions, yellow light travels farther than other visible light. This is why the traffic lights and fog lights of cars use yellow light. For outdoor sports enthusiasts, the outdoor environment at night is usually accompanied by moisture and mist. In this case, a yellow flashlight would be perfect.

Blue light usually travels a short distance and has poor penetrability. However, Blu ray has its own special skills. Blood stains of animals will emit faint fluorescence under the irradiation of blue light. Taking advantage of this feature of blue light, hunting enthusiasts use blue light flashlights to track the blood of injured prey, so as to finally collect the prey.

Red light is the most suitable light for hunters who love hunting. Because many animals are not sensitive to color or even have no color sense, they can brazenly use red flashlights to sweep them when hunting at night, so that the prey gods do not know. In addition, when the line of sight changes from light to dark, it belongs to dark adaptation, which takes a long time and will lead to temporary "blindness", while red light takes a short time to adapt to dark, so that we can better protect our eyes and maintain better night vision when we move at night.

Color rendering index (Ra)

The color rendering ability of the light source to the object is called color rendering, which is compared with the appearance color of the object under the reference or reference light source (incandescent lamp or painting light) with the same color temperature. The spectral content emitted by light determines the light color of the light source, but the same light color can be formed by many, a few or even just two monochromatic light waves, and the color rendering of each color is also very different.

Light sources with the same light color will have different spectral composition, and light sources with wide spectral composition are more likely to provide better color rendering quality. When there is little or no main wave reflected by the object under the reference light source in the light source spectrum, the color will produce obvious chromatic aberration. The greater the chromatic aberration, the worse the color rendering of the light source to the color. Color rendering index is a parameter that measures the ability of light source to show the true color of the object being illuminated. The higher the color rendering index (0-100), the closer the color reproduction of the light source to the natural primary color.