I've made those speedpaintings from a photo references on Shotdeck (a great movie screencaps gallery). It would be better to draw from life to learn more from real condition of light setup, but I currently can't. I want to improve my understanding of color and light, so let's learn from cinema masters :) I use #photoshop and draw on my Cintiq.
That one is a speed painting of the view from my desk, I live in an old factory restored in apartments. At the end of the day the sky was crazy and the atmosphere was gold! I wanted to capture this special atmosphere.