Woman with Flashlight

A flashlight is an essential tool. It’s mission critical equipment no matter what the mission may be. Unfortunately, all too often very little thought is given to its selection.

Tactical flashlights are essential tools, providing illumination in low-light environments or during night-time operations. The ANSI/PLATO FL 1 2016 Standard focuses on light output (lumens), beam distance, peak beam intensity (candela), run time, impact resistance, and water penetration protection. Two additional factors that determine the effectiveness of flashlights are the color temperature and the color rendering index (CRI). They’re important in determining the quality of light. Understanding these concepts can help in choosing the right flashlight.


American Cop has covered lumens and candela in previous articles. In this article, we will look at color temperature and CRI. Color temperature and CRI are both measures that describe the color characteristics of light, but they do so in different ways. It will get technical at times by necessity, so bear with me.

 

Color Temperature

Color temperature scale showing color emitted by a black body on a linear scale from 800 K to 12200 K, assuming a monitor is properly calibrated to sRGB color space. Approximation of the hues of the Planckian locus as a function of the kelvin temperature, rendered with a white point near 6500 K, does not account for chromatic adaption. Vector by Bhutajata / CC BY-SA 4.0 DEED.

Color temperature, measured in kelvin (K) units, refers to the color of light emitted by an ideal black body radiator when heated to a certain temperature. It’s a way to describe the light appearance provided by a light-emitting diode (LED) or light bulb (lamp) and what kind of “white” light it emits.

 

A lower color temperature produces a warmer (more yellow/red) light. In comparison, a higher color temperature produces a cooler (bluer) light. Daylight, for example, is often considered to have a color temperature of around 5500 K to 6500 K, which is why light bulbs with a color temperature in this range are often called “daylight bulbs.”

Incandescent light bulbs typically have a color temperature of around 2700 K (warm/soft white), while daylight is around 5500 K to 6500 K (cool white). A flashlight with a high color temperature (closer to daylight) can provide better visibility in dark environments.

 In practical terms, the kelvin of a flashlight is usually determined by the manufacturer based on the type of LED or bulb (yes, there are still a few flashlights being manufactured using incandescent bulbs) used in the flashlight. Different LEDs and bulbs can produce different color temperatures, and these are often calibrated and measured in a laboratory setting using specialized equipment. The resulting color temperature (in Kelvin) is then typically listed in the flashlight’s specifications. 



A flashlight with a high color temperature (closer to daylight) can provide better visibility in dark environments. It helps to identify objects clearly and quickly, which is often critical in law enforcement and security applications.

Cabot Insurrection 1911 with SureFire X300 Ultra WeaponLight. Color temperature and color rendering are also considerations in selecting a weapon light.

Checking the color temperature of a flashlight yourself can be a bit tricky as it typically requires specialized equipment and a controlled environment. One way to get a general idea of the color temperature is by comparing the light emitted by the flashlight to known standards. For instance, incandescent light bulbs typically have a color temperature of around 2700 K (warm/soft white), while daylight is around 5500 K to 6500 K (cool white).

An App For That

There are also several smartphone apps available that can give you a rough estimate of color temperature. And, if you have access to a digital camera with a manual white balance feature, you can take a photo of a white object under the light of the flashlight. The camera will then adjust the white balance based on the color temperature of the light, which is often displayed in Kelvin.

 

Color Rendering Index (CRI)

 A photography color chart can be used to check flashlight color rendering. However, it’s not as accurate as a spectrometer.


The color rendering index (CRI) is a quantitative measure of a light source’s ability to faithfully reveal the colors of various objects in comparison with a natural or standard light source. It’s a scale from 0 to 100 percent, indicating how accurate a “given” light source is at rendering color when compared to a “reference” light source. The higher the CRI, the better the color rendering ability.

Photopic relative brightness sensitivity of the human visual system as a function of wavelength. High color temperature (closer to daylight) can provide better visibility in dark environments. In humans, photopic vision allows color perception and a significantly higher visual acuity and temporal resolution. Vector by Adam Rędzikowski / CC BY-SA 3.0 DEED.

The CRI of a flashlight is measured using a process that involves the analysis of the light’s spectral power distribution (SPD). SPD is a measure of the strength of a light source at each wavelength in the visible spectrum. It’s typically carried out in a laboratory setting with specialized equipment. CRI isn’t calculated for non-white sources. If the light source doesn’t have a daylight coefficient (DC) less than 0.0054, you won’t see a CRI result. So, the light source of the flashlight must be white for a CRI to be calculated.

High CRI

Light sources with a high CRI are desirable in color-critical applications. However, it’s the CRI doesn’t indicate the apparent color of the light source. That information is given by the correlated color temperature (CCT). In simple terms, CCT is a way to describe the color characteristics of light, relating the color to a temperature on the Kelvin scale. It’s used to measure the “whiteness” of light sources. The perception of “white” is formed by the entire spectrum of visible light,  

A high CRI value allows for better color differentiation. It’s particularly important in law enforcement and security as it can aid in identifying specific features of an object or a person, such as the color of a vehicle, clothing, or distinguishing marks.

SureFire Fury Intellibeam Dual Fuel LED flashlight with Thyrm SwitchBack Flashlight Ring. Agency Arms GLOCK. A variety of factors need to be considered when selecting a flashlight. Color temperature and color rendering are among them.

A photography color chart can be used to assess a flashlight’s color rendering. The chart is illuminated by the flashlight and photographed. The captured colors are then compared to the chart’s known colors.

 


Summary 

Understanding and considering the color temperature and CRI when choosing a flashlight can significantly enhance its effectiveness in law enforcement and security applications. It ensures not only the optimal performance of the flashlight but also the safety and efficiency of law enforcement and security personnel in carrying out their duties.

When purchasing a flashlight, look at the product specifications for the flashlight. Manufacturers often list the color temperature and CRI in the product details. The color temperature will be listed in kelvin (K), and the CRI will be a value between 0 and 1003. 

If possible, try the flashlight in a setting similar to where you’ll be using it. Doing that will give you a better idea of how well the color temperature and CRI of the flashlight meet your needs. 

Human vision can be reduced to 20/60 under streetlamps at night, which can affect an officer’s ability to correctly identify handheld objects in low light. Flashlights can have an impact on officer decision-making in use-of-force encounters.

While color temperature and CRI are important, you need to consider other factors such as lumens (brightness), candela (light intensity), beam distance, and battery life. The best flashlight for you will depend on a balance of these factors. The appropriate balance will depend on the application(s).

 

RESOURCES:

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