Candela question

[lightnix]

If I take two LEDs, each with an output of, say, 500mcd and shine them both onto the same spot would the total output be 1000mcd, or are we dealing with some kind of weird logarithmic scale, like decibels ?

 

[idleprocess]

You're putting out twice as many photons, so lumens should double, but I'm not sure if intensity is additive.

 

[phyhsuts]

Intensity measurement often is a illumination measurement at a given distance. The inverse square law is then assumes and the intensity calculated. This assumes a point source of light. This last do not exist, so all intensity measurement has some errors. If one measures at a large distance from the light however, the error can be reduced to very small amount. The IES suggest at least 50 metres. Under those conditions, two LEDs will give twice the intensity of one.