Outdoors vs Indoors

Outdoors

If you're doing outdoor activities such as camping or hunting, which typically takes place in wide open areas, having a focused beam with more reach (higher candela rating) is recommended.

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Usually, in these circumstances, there is often a need to see what's further down range, rather then what's closer to you. 

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Indoors

If you're indoors, you may simply need a bright light beam with a wider diameter (more lumens) with less need to see further then approximately 20ft, such as you're own house or car garage.

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Self Defense

For self-defense, you need to be able to see further down range so that you can identify a threat quicker and be able to react to that threat.  

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Furthermore, you also need to have a bright light beam that will be able to blind and disorient a potential attacker, giving you critical time to react and take action to protect yourself.  

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Don't ever let a potential attacker get close to you! 

Always create distance between you and the attacker so that you have time to react and take the necessary actions to protect yourself.

To read more about how to effectively use an EDC flashlight for self-defense click on this link...

Lumens

Lets start with Lumens, which are the most common units we use to measure light in any EDC flashlights.  

Lumens simply measure the total visible light produce by any light source or (total amount of light that is radiated.)  

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This is actually pretty easy to measure yourself.  If you point a high lumen light beam at your skin you'll most likely feel the heat.

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Typically, a good rule to follow is: brighter the flashlight more lumens it will have.  

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Lumens can also have an effect diameter of the illuminated area. More lumens, bigger the diameter.

E.g. Moon has an output of 1 lumen.

Candela

The less popular Candela (also known as candle-power) is the measurement of light intensity produced by a light source.  

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Simply think of candela as the intensity (strength) of a light beam.

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Additionally, the intensity of the light beam will also effect the distance the light beam can reach.  

Click on this link to read our complete on Candela and learn about how to best utilize Candela in an EDC flashlights...

The intensity is likely to be determined by the angle at which the light source is emitted as well as lumens.  

Lumens alone will not completely determine the intensity of the light.  

Lux

Lastly, there is also the even less popular lux, but also important to mention.  

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Lux is the measurement of illuminance or the amount of light on any surface per unit area.

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A single lux unit is equal to one lumen per square meter.  

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Think of lux as how bright a surface will be when exposed to a light source.  

Lets Put it All Together

Now that we've learned about lumens, candela, and lux, lets put it all together: 

• In terms of numbers, 1 candela = 12.57 lumens, 1 lumen (ln) = 0.8 candela (cd). 1 lux = 1 lumen per square meter.
• More lumens does not always mean more intensity or Candela
• A focused beam that has lower lumens can potentially be have more Candela then a light beam that has more lumens but is spread wider
• The angle at which the light is emitted has an impact on the intensity of the light and the diameter of the lit area. 
• Lux will be effected by both lumens and candela  
• If you increase the size of the illuminated area without increasing lumens, the lux will decrease 
• Further the light beam reaches, more candela it will have

Diagram Illustrating Lumens, Candela, and Lux

Final Thoughts

Before you decide, which measurement unit is more important, you must also consider what you're using the flashlight for?  

Do you want your light beam to reach more distance, light up a wider area, or just be really bright? 

If you want your light beam to reach further, you will need higher candela rating in your flashlight.  

If you simply need a bright flashlight, without the need for far reach, just higher lumens will do with a wider diameter light beam.