An interesting soft focus read:

THE SOFT-FOCUS LENS AND ANGLO-AMERICAN PICTORIALISM: A Thesis Submitted for the Degree of PhD at the University of St. Andrews ,William Russell Young, III

Download the pdf file from:
http://www.google.com/url?sa=t&rct=j&q=%22imagon%20lens%22%20for%20sale&source=web&cd=15&ved=0CEkQFjAEOAo&url=http%3A%2F%2Fresearch-repository.st-andrews.ac.uk%2Fbitstream%2F10023%2F505%2F6%2FW%2520Russell%2520Young%2520PhD%2520thesis.pdf&ei=9yvNToTPHub40gG98K1D&usg=AFQjCNHOzYNV0lnoEVmbT1dp6e5YeWYvHA

What I downloaded was missing some of the photographs in the thesis.

The thesis discusses Soft-focus, Naturalistic Photography, and Pictorialism from the historic, social and techincal points of view.

Steve