When I was younger I would look at a flashlight beam and it would always just look white to me. It was something that I just never thought about. Once I started doing photography as a hobby, I realized that light had a richness and variety to it that was not obvious to me before. I also learned how characteristics that may not be picked up easily with the human eye can actually have big impacts.
Lighting Throughout Human History
From the dawn of time the term ‘Light’ meant sunlight, moonlight and starlight. Then over 400,000 years ago, fire helped mankind push back the darkness and take control of the night in the form of torches and campfires.
Humans have continually pushed for better and more efficient ways to illuminate the night. We used lamps fueled by animal and vegetable fats, then advanced to kerosene and crude oil. Electricity was discovered and the invention of the incandescent bulb revolutionized lighting. Neon, Halogens, and now LED’s all push the boundaries into the future.
Check out this article for a more complete history of flashlights.
Torches and campfires have a distinct amber or orange color range. As lighting has advanced through time, new lighting techniques brought forward that same or similar warm color scheme. This gave us the familiar glow which resembles the comforting torches and campfires of ancient times.
Fluorescent lighting and LED’s of modern times have broken from that relationship, bringing ever brighter lights with tints of green and blue. These cooler colored lights resemble sunlight or moonlight more than they do fire-based torches.
Every light source has a Correlated Color Temperature (CCT) which identifies the color tint of the light. CCT is measured in degrees Kelvin.
When a solid body is heated (let’s say a metal sword for example) , it starts to glow reddish orange. The hotter the body, the brighter it glows and the more the color that it emits shifts from reddish orange towards blue white. The temperatures at which an object emits light of one color tint over another provides a scale which color tints can be measured.
The Kelvin (K) scale illustrates what color tint is emitted by a black, solid body that is heated to a specific Kelvin temperature. The higher the temperature, the more blue-white the light.
Manufacturers developed Standard Bulb Categories to describe different color tints of bulbs. These Standard Bulb Categories are separated by degrees Kelvin into Warm, Neutral and Cool White ranges.
Fires, candles and lamps that have a warm, reddish orange light color registers as low as 1000K up to about 3000K on the scale. This is the Warm White range.
Neutral White loses some of the redder hues and brings in some bluer tones. These lights produce a more complete spectrum and render colors much better than Warm White. They are also much brighter than Warm White. These colors range from 3100K to 4500K on the scale.
Cool White is the highest Kelvin temperature of the three categories, being over 4500K. It is referred to as ‘Cool’ due to the heavy blue tint being reminiscent of a cloudy or winter’s day. Cool White colors are more reflective of Daylight, being brighter than the other temperatures but also harsher.
Identifying true colors can be important in technical fields such as medical or engineering. Evaluating skin tone or the color of a wire are some examples where a light with high Color Accuracy is important.
We discussed how Color Temperature describes the tint on the light source. Color Accuracy is a little different. It refers to how faithfully colors are reflected from a subject.
The Color Rendition Index (CRI) has been the longtime standard for measuring Color Accuracy. CRI uses a color palette of 8 specific colors evenly spread across the visible light spectrum. A CRI score of 0-100 depends on how accurate these 8 colors are reproduced.
The problem with CRI is that it assumes a full spectrum light source. Most LED’s have a light curve with peaks and valleys, including gaps where these specific colors live. This can give CRI scores that are very misleading.
The Indie Cinema Academy has an excellent video on CRI and LED’s here.
Color Accuracy is not touted in many of today’s LED flashlights, probably because of the full spectrum issue. However, it is worth looking for if you need it. If there is no CRI or Color Accuracy score, one way to gauge Color Accuracy is by using Color Temperature as a guide.
- Enhances Red and Orange colors
- Blues are darker and can appear almost Black
- Whites appear strongly Orange or Yellow
- Neutral appearance
- Enhances most colors equally
- Doesn’t favor Yellow or Blue
- Enhances Blues
- Flattens Reds
- Adds a Bluish tint to White
For best Color Accuracy, select a Neutral White option if there is not a CRI or Color Accuracy rating for the flashlight.
Physical Impacts of Color Temperature
LED lighting has taken hold and is replacing Incandescent or Halogen bulbs around the world. As this is happening, the effect if the newer LED’s and their different color temperature has come to light.
Melatonin is a natural hormone that relaxes the body and makes sleep more inviting. Warm White light mimics the campfires and torches that mankind has relaxed too since prehistoric times, and facilitates Melatonin production.
More specifically, it is the absence of blue light that facilitates Melatonin production. Cool White light more closely resembles daylight, which is when we are traditionally more active and alert. The blue wavelengths in Cool White light block Melatonin production in the body, helping us keep more alert.
Personally, I am particularly vulnerable to Cool White lights disrupting my sleep cycle. I’m kind of a Color Temperature cop when I’m out in the woods with a group.
LED screens have been shown to have a damaging effect on the Retinas, particularly in children and the elderly. These concerns are related to LED screens specifically, which put a high amount of light directly into the eye.
Flashlights have a much more intense light than a phone screen, but unless you are shining one directly into your eye the light is more indirect. However, LED screens share the same spectrums of light as LED flashlights, especially the Cool White variety, so the same concerns and cautions regarding artificial lighting apply.
It is also easy to lose your night vision using bright LED lights at night, particularly with Cool White colors.
Which Color Temperature Works Best?
For me it is important to use the right Color Temperature for your specific purpose, but usually you just need to use the flashlight that is handy regardless of the beam tint. When making a buying decision it is best to evaluate what you will mostly be using the flashlight for, and select one that fits the majority of your needs.
Warm White flashlights are definitely easier on the eyes and body than other temperatures. They help maintain sleep cycles and night vision. They create a calming environment, and are preferred at night when you are winding down.
The reddish-orange colors in the Warm White range have a longer wavelength. They are generally not as bright as comparable lights with blue tints.
Warm White flashlights also have less scatter. Opinions vary, but it is thought that lights in this spectrum cut through fog and rain better than others.
What they are best for: Campers, hikers and outdoor enthusiasts. I always keep a few Warm White flashlights for power outages.
The blue tint of Cool White bulbs makes us more alert and attentive. These are the brightest lights and are very good for illuminating workspaces. The brightness and intensity make these bulbs a good choice for ‘thrower’ lights such as searchlights that need more distance.
Cool White bulbs do have a shorter wavelength than Warm White bulbs which causes scatter and glare. This is believed to make them inferior to Warm White bulbs for fog and rain.
What they are best for: Searchlights, Work lights.
The Neutral White spectrum is the middle ground between Warm and Cool White. Neutral White bulbs give most of the brightness of a Cool White bulb while incorporating the more pleasing warmer tints. These flashlights are much easier on the eyes than cool whites.
The more complete spectrum of Neutral White allows for the best color reproduction. For any role or purpose where correct color identification is crucial this is the best option. This can include paramedics and other first responders, engineers and electrical workers.
What they are best for: Accurate color reproduction, general high quality light.
What is the Best Color Temperature?
Color Temperature is a very important factor when selecting a flashlight. Check out this article for more factors to consider. Don’t just buy a torch because it is super bright or looks cool. Knowing how you will typically use your torch will help you make the right choice.
Personally, I always go for the Neutral White options. I prefer the higher Color Rendition and feel that they are bright enough for almost anything I need, while still being easy on the eyes. My wife is different – she prefers Warm White. Others that I know swear by Cool White lights, but I am not a fan myself.
Although each has its strengths and weaknesses, and best usage scenarios, the choice usually comes down to your personal preferences.