Candela: The desired intensity can also be specified by required candela value. In our calculations, we always use Effective Intensity to measure a light’s brightness, which is the intensity that your eye perceives when looking at a light. In the case of a flashing light, the human eye will always perceive a lower value than the actual output, known as Peak Intensity, of the LEDs. Our calculations compensate for the fact that the LEDs will need to be driven to a higher value to achieve the Effective Intensity requested. Calculating using Effective Intensity instead of Peak Intensity ensures you get a product with the light output you expect and the right solar engine to perform reliably.