Lumens vs candlepower?

[shootist16]

Does anyone have a forumula to convert these measurements? Streamlight measures theirs in candlepower and surefire uses lumens. I would like to be able to compare these measurements.

 

[razcob]

Candlepower is a rating of light output at the source, using english measurements. Foot candles are a measurement of light at an illuminated object. Lumens are a metric equivalent to foot candles in that they are measured at an object you want to illuminate. Divide the number of lumens by 12.57 to get the candlepower equivalent of an LED light source. This calculation is does not factor in lens or reflectors. This is absolutely no help at all.

 

[Orm]

Shootist16,

The problem about converting lumens into candlepower (and vice versa) is that it's all subjective (candlepower being preferred by manufactures as it gives some high figure result once you've focused the beam down to that of a pin-head). I won't go into all, as I'm just about to go to bed, however check out these two links from www.candlepowerforums.com :

http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=002225

http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=002416

There are probably many more discussions about this over there, but I only did a quick search.

Hope this helps.

Orm.