Question Backup lights

[Ale C.]

Apologies if that was just stating a bunch of stuff you already knew.

No not at all. I'm not very physics talented so it took me many efforts understanding the gas already, really not want to start again with light.

I'm aware of lumens, and lux, but never candela. Just wondering, is there a way to convert these for comparison if the manufacturer does not provide a consistent measurement?

Cheers,
Ale

 

[stuartv]

No not at all. I'm not very physics talented so it took me many efforts understanding the gas already, really not want to start again with light.

I'm aware of lumens, and lux, but never candela. Just wondering, is there a way to convert these for comparison if the manufacturer does not provide a consistent measurement?

Cheers,
Ale

My bad on that. Lux and candela are very similar in concept (but not the same). I should have explained that earlier.

There is not really a direct conversion between them as they are all different.

Lumens is total output.

Lux is output per surface area. I.e. Lumens per square meter.

Candela is brightness from a certain distance. If a light source disappears from view when you get 1 foot away from it, then it is 1 Candle-foot in brightness.

Hopefully, this illustrates why Lux and Candela are similar in concept, but not exactly the same.

Evaluation of lights/torches is complex. Lumens output, beam angle, amount of spill (the less bright halo of light around the bright spot in the middle), and many other factors are at play.

I start with lumens and beam angle and go from there. Those two specs do not tell the whole story, but they usually tell the main plot.

 

[Ale C.]

My bad on that. Lux and candela are very similar in concept (but not the same). I should have explained that earlier.

There is not really a direct conversion between them as they are all different.

No worries, very helpful for me to start, thanks mate.