I'm sorry AT - every image from post 11 on has problems and so do some of the originals.
The main problem is that they are were shot in too hard light without fill flash - so they are underexposed to the point where you can't see the detail.
Given that the dude is an artist, and you are taking pix of his work, the work should imo be full of detail.
Your last colour shot is COMPLETELY off in colour.
Personally....I would reshoot these if possible.