Choosing the Right Light
It’s recommended that users consider two light measurement factors when choosing a portable light:
Total Light Output
Lumens are a good measure of the overall visible light energy.
It may be the total light coming from a bare bulb or the actual
measured system output of the lighting device. It is largely a
function of the light power of the bulb or LED. Lumens do not
indicate how bright a target will appear. Manufacturers use an
integrating sphere to measure lumens.
Peak Beam Intensity
The brightest spot of focused beam is expressed in candela. It
is a function of the bulb and the effectiveness of the reflector in producing a focused beam. It yields a good representation of the tightness of the focus and the apparent brightness of the light on target at distance. Manufacturers use a photometer, usually 100 feet away, to measure Peak Beam Intensity.