Basic info to determine flashlight performance

GA Firing Line

ZuluFoxLights

Hunter
May 14, 2017
17
8
13
Atmore, AL
www.zulufoxlights.com
Zip code
36502
This is a post directly copied from the blog on my website. It gives a little insight on what you should really be looking at when comparing flashlights. It will help you be more informed in your decision as to which flashlight will best suit your needs when choosing between the myriad of options.

Here is the link to my website blog article.
https://www.zulufoxlights.com/single-post/2017/06/27/Basic-info-to-determine-flashlight-performance
https://www.zulufoxlights.com/single-post/2017/06/27/Basic-info-to-determine-flashlight-performance


Basic info to determine flashlight performance


June 27, 2017

T.K.




This blog post is for folks wondering what they should really look at when deciding between the myriad of lights to purchase. I will attempt to give you some knowledge on how to determine if a certain light fits your needs. I will start by explaining the popular ways lights are advertised and what people react to when reading the ads, what you really need to look at, how to interpret the data, and how all of it colludes into a baseline for comparison between items you wish to use. Mind you, this disregards runtimes and power source selection, but I will touch on those at the end.

First and foremost, stop believing everything you see on the package. Why? Most light manufacturers do one or a few things to make their lights seem impressive. Firstly they overstate the actual ratings of the hardware and performance capabilities of their products. Example: The “derpbrand” AA pocket sun is capable of producing 600lm and running for 2hr. Straight up that is not right. Science says that is not fully possible….unless you bend the rules a bit. Secondly, they normally only list the information that sounds good, such as lumen output, beam length, and run time; missing an important number.

People are drawn to big numbers. The higher the number of lumens, the more badass of a light right? Nope….absolutely wrong. Same with beam distance, the longer the beam distance the better the light right? Wrong again. The only reason the companies list those numbers is to draw you in and make a sale on one of their products. Granted, lumens plays an important role in performance. Beam distance is a solution to an equation between lumens, die size, beam angle, and reflector size. All of these numbers are relatable information but not exactly what we want to compare our light with.

This is what you really need to look at. I’ll start with the basics and finish with the most important number. Firstly, look at the lumen output. Lumens is the measurement of total light output from the LED itself. Example; the total amount of water that is coming out from the end of a waterhose. Secondly, observe the shape of the reflector, for depth and circumference. Why? That measurement + lumen output + a few other sciencey measurements determine the “beam distance”. Thirdly, look at runtime. Compare the runtime to the type of power source the light uses. If they are stating that you can get a “insert high number of lumens” for “insert crazy long runtime” from an “insert small battery size like AAA”, then most likely they aren’t giving you the details how that runtime is measured. That should give you a red flag on how the rest of their measurements are take and stated. Lastly, I will touch on the most important number when determining the usefulness, viability, and performance of a flashlight. That number is called Lux.

Lux is the measurement of “the amount of luminous flux (lumen) per unit area”. 1 lux is equivalent to 1 lumen per square meter at a distance of 1 meter. In laymens terms, the “intensity” of the light is what lux is: not the brightness, as brightness and intensity are actually two separate measurements. Example: the water pressure coming out from the end of a waterhose. The higher the lux output of a flashlight measured at a given distance, the more intense it is, which in turn means it is perceived as more powerful by the human eye. Lux is affected by a lot of factors to include; led die size, beam angle, reflector size, lumen output, atmospheric conditions, and the luminous emittance of materials the light passes thru i.e. the lens or optic installed in the flashlight.

What I am saying is, you can take two flashlights that both output 500lm, but one has a more intense light beam at 50yd than the other. Why? Because it has a higher lux due to the other factors that determine overall Illuminance of a light on a surface at X distance. This is why you cannot take lumens as a measurement for overall performance of a flashlight. I can make a 500lm light shine farther and appear more intense than a 1000lm light just by changing some variables in the lux equation.

How do you use all of this information to form a comparison between lights? First, look at the lumens as it determines the overall light output from the LED. Depending on the amount of light you need, adjust that number to something you need. Next, observe size of the reflectore/optic (depth and circumference) shallow & wide make for a less intense and more floody beam, deep & narrow make for a more intense and spotlike beam. Thirdly look at beam distance. A lot of lights don’t list the lux on the package or inserts. You can get a rough idea of the lux by looking atbeam distance. Generally, the greater the beam distance means the higher amount of lux. With all of this in mind, look at it this way. Need a lot of light up close and personal but won’t blind you? Pick a light with high lumens and lower lux. Want a little amount of light up close that will make you see spots? Pick a light with lower lumens and higher lux. Want a lot of light to shine a long long ways? Pick a light that has a high lumen and high lux rating. Want a little bit of light that can shine a long ways? Pick a light with lower lumens and a high lux.

I will touch on runtimes and power sources real quick to finish. Firstly, the runtime is mostly determined by the maH rating on the battery and the amount of current the LED driver draws. If I have a 3000maH aka 3 Amp Hours battery and run an LED at 1.5A, then my light will theoretically run for 2hr before dying. Easy eh? More lumens = more current draw = less runtime on a battery with X capacity.

Power sources….this is strictly opinion. I do not recommend using a light that takes an alkaline or any other primary battery whether single, in series, or in parallel, except for lights that run on cr123a. Why? Because technology has improved to the point where low capacity primaries such as AAA and AA batts are not considered as power efficient and cost effective as they used to be. I recommend the cr123 simply because it has become an industry standard by way of monopolization from the big box brands. My recommendation as a power source for flashlights now is a Li-Ion rechargeable battery in an equivalent size to the primary counterpart for the given implementation.

Thanks for reading guys! I hope this helped!

As always,

Semper Fi & God Bless