I am now beginning to introduce a wider tonal range. There is a light mass and now two different levels of dark. I have gently begin to break up the light mass based on the forms of his face. This is more difficult in life than with a live sitter - you really have to push yourself to see a lot of those midtone/transition areas. The shading on and under the mustache is pushed together with the shading on his face - there should be no distinction in terms of the cause. The light is still blocked, whether it be because of the face turning away from the sun, or due to a mustache, nose or ear obstructing the passage of light. As I mentioned before, it should appear as if you are squinting at the sitter, only now we have our eyes opened a bit more and we can start to see more of a range of light to dark.
Also, look at this stage next to the previous one - though it appears that I have lightened the background next to his cheek, I have not. It is an illusion created by adding the next range of shadow to the side of his face and darkening his jacket. It's all relative.