The PACE Gallery has the Irving Penn, "On Assignment" exhibition currently showing.
One of the highlights for me was seeing his communication/selection method he devised for the various editors he worked with.
He produced two identical proof books and sent one to the editor so they could both be looking and discussing the same image over the phone. The editor then sent the book back to Irving to update the proofs for their next selection conversation.
You can imagine how long this took back in the 40's!