Last summer while antique shopping out in West Texas, I asked a dealer about old lenses and he pulled out a large, dingy lens on a 6 inch square lens board. It made an image, but I could not tell what optical design it was just by that incidental inspection. It was marked for $4000 (a sucker is born every minute, right?), but I told him I'd be happy to walk out with it for $300. He said how about $500 and I said deal. Once I got back home with it, my research showed it to be a Voigtlander & Sohn #4 "pre-Euryscop" from about 1879. This is a Rapid Rectilinear of 14.5" at f/6 (these are normally built at around f/8). So although it was not the Petzval find of a lifetime, the dealer and I did not do badly by each other--these have sold for both more and less than our deal. It is perfectly all right for studio portraits as well as for landscapes.
I learned also that the lens can handle up to 11"x14" fields when used stopped down (via a Waterhouse slot) or close up (the cone diverges enough to reach the corners in this case). I recalled a friend's suggestion one time that I might consider adding a rear adapter to my 8x10 view camera for large format, so I went to work. A 12"x12" wooden "canvas" from a hobby store was perfect for mating to the rear of the view camera. I cut up some luan plywood paneling to build the extension box, and quickly hacked together this extension. I decided to model the back side to accommodate the frame of an 11x14 picture frame from Dollar Tree since I knew that item would be a stable source of good, thin glass for wet plate coating. What was missing, though, was an actual working design for a plate holder and focuser.
Earlier this week, as I gazed on the flimsy plastic frames I had liberated this plate glass from, I realized that I could stack two frames (secured firmly together by 3 #4 brass screws per side) as the cassette and use the gap in between as the guide for a dark slide. I used a table saw to dado a wide cut across the end of one frame for inserting the dark slide. Likewise, I could stack another two, and I had my ground glass adapter. The backing cardboard could be used as the dark slide since it was already cut to fit. A pair of the hanging hooks doubled as spring clips to keep the contraption in place. And Dollar Tree sells kitchen cutting mats, 2 for $1, that are 11x14" with a matte surface that drops right into the focusing frame like it was made for it. Today I got to try out this cheapo hack, and it did its job like a champ. My first effort was slightly underexposed, but it proved the concept of using an extension back to get new use out of a smaller view camera. This was also my first large format pour, harrowing to step up to but exactly like using the smaller sizes in practice.
When I researched extension backs, I got a confirmation of the design from a Blair Reversible Back from the 1890s. I would do a few things differently next time, but that won't be until something breaks. http://www.piercevaubel.com/cam/blair/blrbi.var3.htm