Lux V Candela

So I've recently gotten back into flashlights and weaponlights and I've noticed a new (to me) measurement of "throw." Year's back it seemed like the only measurement for throw was Lux. Now I'm seeing Candela. That's all fine, but the problem I'm having is comparing the two. For example: Malkoff lists their numbers in Lux and folks like Modlight, Cloud defensive and even Surefire are listing in Candela. How can I compare directly the numbers from Malkoff to the other guys? Is there a conversion or are they completely different measurement parameters? Thanks for any and all help!

Lux is a measure of intensity (lumens / meter^2) and can be taken at any distance. Candela is lux at a distance of 1m. Usually when a light is rated in lux they mean 1m distance, but I have seen some use 5m. Because of this, some people use lux and candela interchangeably even though lux should always specify a distance.

^^ Exactly.

I prefer the term candela used by a light maker because it tells me without thinking real hard if it is a thrower, flooder or in between. Yet a lux number can provide that too, it's that I'm used to seeing candela mentioned these days.

To me lux is used by military type lights where candela by civilian based lights. Not always the case but just what my brain thinks when I see the two terms.

Old thread but your answer to me on the Olight thread got me to searching and i found this. Surprised it didn't get more input? I think there is more here to learn or maybe not?

We don't seem to have nearly the knowledgable userbase as they did here 20 years ago.

Twenty years ago many of the discussion topics were related to the tint lottery, light engine mods, and hardware in general, with less attention devoted to the nuances of light measurement and the quirks of human vision. That noted, there are several older threads that get deep into the weeds of human color perception and similar arcana. The knowledge base is still here, if you know where to look for it. 🔬

I miss when you wander into a thread and many individuals are debating or discussing matters on a very technical level.

Buff said:

Old thread but your answer to me on the Olight thread got me to searching and i found this. Surprised it didn't get more input? I think there is more here to learn or maybe not?

Click to expand...

It really depends on how far down the rabbit hole you want to go @Buff . Post #2 should allow you to understand the answer you seek. I like the term candela because it gives you the info at the same distance every time. It helps me understand whether a beam is like a pencil or a flood light or in between.

I have a pair of Pelican 2350's for example. The 100 lumen version has 19k candela. The 175 lumen version has 9k candela. Now obviously the 175 lumen one is "brighter".

But by knowing what cd means I know the 175 version is great for lighting up a dark shed and the 100 one is better for seeking out my dog in the woods or spotting eyeballs of critters. Plus my peripheral vision is less affected.

For home defense for example the beam of the 100 lumen one will blind a perp inside my home without all those nearby lumens blinding me. 😱

I have a Maratac Rebel throw its the brighter beam in my Avatar. I think it's over 6000 lumens and 90k candela. It's so bright and beam like if i was to light up a deer and it was standing in front of a wall i wouldn't see a shadow on the wall. It would be an Xray!
My Maratac Tri flood is over 10,000Lu and it too is super bright but as the name implies a total flood.
3 emitters and that orange peel behind the lens will do that.

Quick Summary: Lux or Candela shouldn't make any difference. Except the vendor does it wrong :- )

Lux vs Candela? Ha! It's not about two but at least about three:

• Lux - the illumination at the target, the spot.
  Always keep in mind questioning: taken at 1m? (OK, that's the usual case), or another distance (then you'd have to recalculate)
• Candela - the luminous intensity of the source in a particular direction - that's the proper unit.
  Usually it's easy: The number for Candela is the same as if you had measured Lux at the distance of 1m (~3.3ft). And for any other distance, you would just recalculate.
• Candlepowers - a historical unit. It's quite similar, but not exactly.
  Why any difference to Candela at all? Before the Candela was defined, countries had different ways to define a "normal", using real lamps with specific dimensions, fuel etc. Example links: US, France, Germany, and so on.
  After all, the issue was settled with a common, reasonable and scientific definition, the Candela.
  The historic Candlepower is equal to 0.981 Candela. That slight difference wouldn't be a problem for us flashies. But guess what happened then: Crazy fantasy specifications for some US warehouse handheld lights. And then, some chinese chimed in and also tried their best about notoriously exaggerating some values...

Why Lux at all? (instead of Candela? Strictly speaking, Lux is just not the correct unit, anyway.)

Lux might have been in use for a long time, because it's just closer to what you do in practice: There is no "candela meters", only "Lux meters". You take your luxmeter and read "Lux". But I hope you also have taken the distance to the source. Becaue Lux is all what your device can tell (without having a range finder built in :- ). Thus you either measure Lux at 1m, or you recalculate after measuring the actual distance. And often you even shouldn't use the close distance of 1m: Especially big throwers and/or lights with a high lens diameter only should be measured at much higher distance, where the beam profile is becoming uniform...

bykfixer said:

I like the term candela because it gives you the info at the same distance every time. It helps me understand whether a beam is like a pencil or a flood light or in between.

I have a pair of Pelican 2350's for example. The 100 lumen version has 19k candela. The 175 lumen version has 9k candela. Now obviously the 175 lumen one is "brighter".

Click to expand...

I guess if the lights have similar Lumens, then comparing Candelas can work, thinking about "pencil" or "flood".

But keep in mind: strictly speaking, Candela or Lux really doesn't tell anything about "pencil" or "flood". Without the Lumens information, this only tells about one very direction of your beam. It doesn't explain whether you only have a tiny laser-like pencil beam with some spot-Lux, or some enormous flooder enlightening the whole field with these Lux (what a difference...)