This week at the Wednesday night figure drawing session at Studio b, instructor Heather Clements gave a demonstration. I love watching the magic of an artist working. The transformation of the blank surface is mesmerizing.
Tonight Heather was continuing with last week’s focus on light and shadow, to define shape. 
She showed examples of high-contrast lighting (Andy Warhol’s self-portrait), where only two or three values with very distinct edges are mapped out, as opposed to tonal development with a full range of values (self-portraits by Edward Hopper and Chuck Close). She talked about local values, such as dark hair vs. light face, and then she reminded us about various effects to look for: the lit side of the subject, the unlit side, the midtones, the highlight, reflected light, and the cast shadow, including how a cast shadow is sharply focused close to the object, but less focused further away.
Heather also gave a demonstration on the reverse process, toning the paper overall and then erasing the lighted areas, and perhaps adding some darks at the end. I was happy with the results of my effort towards this reverse process (at right).
You have some beautiful drawings here. Very lovely.