Thomas902 wrote:
"...For DX cameras, Nikon has a Nikon 40mm F 2.8 G DX Micro Nikkor that is very good..." yep, I have this optic also... stellar, one of the very best DX Nikkors available... only limitation is it's close working range... makes it virtually impossible to illuminate your subject...
So long as the subject is static, not much working distance is needed. Side lighting enhances surface texture and with a pocket flashlight like a Nemo “Lil Larry” or “Big Larry2” 10mm or so is plenty of working distance.