This is my first digital self portrait and only about the 3rd or 4th self portrait I've ever done before. It is so hard to make sure when I looked back in the mirror that my head was in the exact same position. Especially when I hadn't gotten much sketched out yet. I realized a ways into it that I was facing the screen more when I was looking a the mouth/chin/neck region than when I was looking at my eyes. Once I fixed that, the portrait started looking more like me.
Mass Light - If it faces the light, it's gonna be mass light. And that is going to be lighter in value than any part of the shadow.
Transition/Half tone - The curve of the surface really affects how quickly the values change from highlight to transition
Highlight - The surface texture/material really affects the highlight. The highlight appears to be a fairly significant step up in value from the lighter portions of the mass light.
Mass Shadow - Opposite of Mass light, if it faces away from the light source, it's gonna be mass shadow and that will be darker than the darkest part of the light.
Fill Light/Reflected Light - I was able with my setup to minimize the amount of reflected light, at least on the shadowy side of the face, but anytime there's a plane that faces the light close enough to a plane that faces away from the light, the value is lighter
Core Shadow - The planes that are most turned away from the light have the core shadow, unless they're being affected by reflected light or a fill.
Cast Shadow - This seems particularly dark in value, and the edges of the shadow are sharper than transition and fill/reflected light.
Eager for feedback and I want to work on this some more. Every time I come back to it, I see new areas that need work. Man, painting from life is hard!
This is looking great. For such a soft value range I think you have captured the values very well. I think some more painterly brushes would go a long way in adding interest to the background and surface of the piece. The edge work on the piece is very nice. I think right now the hair could use more shape carving so it has less digital airbrush vibe going on and more observed shape definition. That's all I can see at the moment.