Information and discussion on all aspects of British photographic history
Hi, David. Thank you for replying with the 1852 reference. "Non Inverted Collodion Portraits" is referring to a glass plate [maybe ambrotype] process which can be laterally reversed. Yet it's a marvelous advert touting the benefits of collodion "without Metallic Glare" as opposed to "hard" metal-based imagery on daguerreotypes and tintypes. A 14 August 1852 article, also appearing in the Norwich Chronicle about Villiers, mentions "The new process by which portraits can be taken on glass is now being adopted in this city. ..."
I am making slow progress and found copies of an 1839 drawing of a Giroux with a lens mounted correcting mirror, and an 1847 French reference having an illustration of a correcting mirror assembly with exposure flap that would mount on the front of a lens barrel. The English translation of the French reference says: "Accessories and utensils used in daguerreotype experiments."