Attached Link: Bronwyn's Portrait

That makes sense, but how do we know what values are "right?"  And wouldn't these change, depending on the lighting conditions?  (I have a really tough time rendering low-light scenes.)  For some of us, there's already so much complexity in the shader tree that it feels overwhelming.  This portrait, for example, is of a character that uses one of Robin's shader trees for the skin.  When I go into the materials room to have a look at what she's done, I have NO CLUE what most of those nodes are actually doing.

 

Now, despite Robin's excellent work, I would NEVER mistake this render for a photo.  The hair, Bronwyn's nose, and her flesh simply don't look real to my eye--even though this is my character and my render.