I found a photo of Col. Nelson to go with my bio of him, for my book "More Generals in Gray" (LSU Press 1995). The photo was from the South Caroliniana Library. I've also been in touch with his descendants.

You appear to be seeking photos of Confederate colonels. My book on Confederate army colonels has been accepted by the U of Missouri Press for publication, and when it comes out may be of help to you.