just sketching around.
Basemesh and sculpting done in blender. Zbrush was used for sculpting and rendering. Photoshop for DOF. retouching, vigneting done in motiva RealCamera
Only the Head is modeled. The rest is HDR image. Used Zbrush's auto lighting and shadows based on the HDR map.
bottom one is without post work just so you can see how well ZBrush matches the look of the background image. Love that.