Candela vs Lumen

V

Verbal Clint

New member
Just wondering which you guys consider more for a tactical light: candela or lumens. The reason I ask is this...there are VERY FEW situations I can think of where I would need a very wide field of view with a flashlight. I typically don't make it a point to find myself out of my car in a place that is so poorly-lit that I need a tac-light. However, if I'm at my house where the biggest FOV is one end of the living room to the other, I can really see myself needing some light power. Thoughts?
 
It depends. I have a very large room in my house that has a lot of furniture. I like having a very wide field of light in that room instead of a bright directional light. For the rest of the house I prefer more of a directional bright light.

During clearing operations I used a helmet mounted light for looking around and a issue Surefire on the rifle. The SF while heavy, threw out a huge near sun like directional beam while the head light allowed me to do a number of other things without lowering my weapon or using another hand. The arrangement worked very well and I have essentially adopted it for home use.

So for HD my suggestion would be both. A weapon mounted light with a high intensity directional beam and wider head lamp beam.

For SD I don't carry a weapon mounted flashlight, just my regular flashlight on the belt. For my plans this is adequate.
 
Candela and lumens are just two different ways of measuring light output.

As I understand it, Candela is based on the level of highest light intensity in the beam while lumens actually measures the entire light output of the device.

Neither measurement tells you a lot about whether you will get a tight beam or a diffuse beam, that has more to do with the design of the light.

All else being equal, a large smooth reflector has the potential to provide a tighter beam while a small reflector, or a reflector that is textured will tend to provide a more diffuse beam.

Inside a house, where walls and ceilings are typically light colors, you get a lot of scatter. You can often illuminate an entire room surprisingly well by shining the light at the ceiling in the middle of the room.
 
+1 JKSA

As an example, assume you have a 5mW laser and a 1W LED light on your pistol. The laser has all of its photons in a super small column that does not spread out much from you pistol out to 100 yards. The LED light has a much lower intensity than the laser but gives off 200 times more photons. Since the light spreads out rapidly, you can't see squat at 100 yards with it.

The laser has a massive intensity ie.; high candella value but very few lumens. You can illuminate a super small area (say 1/4" diameter) at a very long distance, but can't see squat 2" away from the laser dot.

Conversely, the light has substantial lumens but lower candella. You can see most everything in a decent sized room but not much further out.

So to your question, If you want to aim, quickly target, or blind the opposition (permantly or temp) it's pure intensity (candella) delivered on-target. If you want to be able to see a wide area quickly then it's lumens.

Does that help any?
 
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Inside a house, where walls and ceilings are typically light colors, you get a lot of scatter. You can often illuminate an entire room surprisingly well by shining the light at the ceiling in the middle of the room.
Click to expand...

In a house with light walls you can actually get pretty good effects with a green laser too. Just not in my house.
 
Also, ad to this equation, that the tac light is often used more for other uses than it is tactically...so you may want a light that serves the other purposes well, too.

To answer your question, lumens rule the day for me now as this is the primary descriptor assigned to most lights now and it is easy to understand and see the difference for me as I am mostly uninformed as to what most of the specs on flashlight mean.
 
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Yeah... Who is using Candelas these days anyway?

I used to see LEDs spec'ed with those, but not so much anymore.
 
It doesn't really matter because the light manufacturers don't use the same method of measuring output whether it be candelas or lumens.

For example, most of the LED-based flashlights that use the same LED will have different output ratings. Some just use the lumen output spec provided on the LED manufacturer's spec sheet. And some will take into account optical losses (from the reflector, lens, window, etc.) and electrical losses (diminishing battery power). So it is possible to have a flashlight with a 100 lumen rating and another flashlight with a 500 lumen rating, and still have greater visible output from the 100 lumen flashlight.

The eye isn't equally sensitive to light at all wavelengths, so it is possible to have a flashlight with an extremely high lumen rating yet still difficult to see with. In a case like that, the output may be biased to to IR or UV portion of the spectrum, or it may be extremely narrowband, with a white appearance, but most of the emission in the blue or green area of the spectrum.

Sunlight appears white to us because the sun has a very broad (high bandwidth) spectral output. LEDs appear power efficient because their spectral output is more selective with lower average bandwidth.

So to answer the question -- just get a flashlight you'd enjoy owning!
 
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