What is Luminous Flux?
Luminous flux is a measure of the perceived power of light or light intensity. Because luminous flux is the measure of a property in the perceived sense, it is adjusted to deal with the fact that the human eye is sensitive to many different wavelengths of light and in different ways. Luminous flux is able to account for this sensitivity by weighting the power at each wavelength of light with a luminosity function that represents how the human eye responds to different wavelengths. In other words, because the human eye does not have a uniform response to all wavelengths of light, we have to weight our calculation of luminous flux to our understanding of how the eye responds at the different wavelengths of visible light. To determine the total luminous flux from a given source, we do a weighted sum of the power for all wavelengths of light within the band of light that is visible to the human eye. Because luminous flux depends only on the human perception of light, all other wavelengths
