The Illuminating Engineering Society now offers the IES Ready Reference App, a free app that provides core lighting knowledge, general information from the IES Handbook and IES standards, and a simple calculator for basic lighting and economic calculations, and a search feature.
Education + Resources
Gigahertz-Optik Publishes Tech Article on Basics of Light Measurement
Gigahertz-Optik has published a technical article providing an introduction to the radiometric, photometric, colorimetric, reflection and transmission principles as well as quantities, symbols, units and the basic nature of light and color.