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How to convert Candlepower to Lumens???
- Thread starter Slaytanic
- Start date
Keep Supporting real Metal!!- Joined
- Oct 3, 1998
- Messages
- 4,842
No conversion between the way candlepower is normally measured, and lumens.
This part of the web paged cited is right but misleading:
When you see a candlepower measurement from a manufacturer, it's usually a measurement of only the brightest part of the beam.
When you see lumens, it's the sum total of all output. Sometimes this is measured using the reflector etc. and this results in lower numbers (e.g., Surefire), sometimes companies measure the total light coming out of the source without using the reflector which results in higher numbers (e.g., most other companies).
So, manufacturer's candlepower measurements are brightest part of the beam (a pencil-thin beam that's very bright would have high candlepower even though total light output is low), and lumens are measured as total output but say nothing about the brightest part of the beam. It's a simple exercise to see that you can't convert from one to the other. There's no way to derive total light output knowing just how bright one part of the beam is, and there's no way to derive how bright the beam is knowing only the total output. And to confuse things, companies measure the outputs using different methods, to make their lamps look brighter than their competitors'.
This part of the web paged cited is right but misleading:
When you see a candlepower measurement from a manufacturer, it's usually a measurement of only the brightest part of the beam.
When you see lumens, it's the sum total of all output. Sometimes this is measured using the reflector etc. and this results in lower numbers (e.g., Surefire), sometimes companies measure the total light coming out of the source without using the reflector which results in higher numbers (e.g., most other companies).
So, manufacturer's candlepower measurements are brightest part of the beam (a pencil-thin beam that's very bright would have high candlepower even though total light output is low), and lumens are measured as total output but say nothing about the brightest part of the beam. It's a simple exercise to see that you can't convert from one to the other. There's no way to derive total light output knowing just how bright one part of the beam is, and there's no way to derive how bright the beam is knowing only the total output. And to confuse things, companies measure the outputs using different methods, to make their lamps look brighter than their competitors'.
Gollnick
Musical Director
- Joined
- Mar 22, 1999
- Messages
- 29,258
Lumens are measured with a device called an integrating sphere. It measures the gross amount of light produced from the source.
Candlepower is measured at a specific point. If the light source produces a single, colimated beam, the Lumens and Candlepower can be related. But, that is a very exceptional case.
Candlepower is measured at a specific point. If the light source produces a single, colimated beam, the Lumens and Candlepower can be related. But, that is a very exceptional case.