6½ x 8½ Extra Rapid Universal Series D. No. 796924
Bausch & Lomb Optical Co., Rochester, NY
This nice little brass lens is approximately 9¾ inch focal length (estimated by mounting the lens on a Sinar Norma using a universal iris mount, focusing on a distant horizon and measuring from the film-plane to the aperture ring). The aperture ring is marked 64, 32, 16, 8, 4, 2.2, which I believe is in the early Uniform System (U.S.) established by Britain’s Royal Photographic Society in 1881. In contemporary f-stop markings this would be f/ 32, 22, 16, 11, 8, 6.3. The ring does move stiffly through the whole range, but the lubricants are dried out. The lens will need a good CLA (Clean, Lube & Adjust). The aperture blades are in fine condition.
There is some separation showing on the edges of the front and rear elements. As can be seen in the photographs, the brass barrel has scratches and marks, and the glass has some dust and scratches typical of a lens of this age.
This fairly compact lens measures 2½ long (63.5mm), with the front an rear diameters ~1.9 inches (49mm). It would require a 2? inch hole to mount on a lensboard.
Includes original lens flange and non-OEM lens caps.
The Rapid Rectilinear is a lens that is symmetrical about its aperture stop with four elements in two groups. It was introduced by John Henry Dallmeyer in 1866. The symmetry of the design greatly reduces radial distortion.
— From Wikipedia, Rapid Rectilinear
— Anthony's Photographic Bulletin, Volume 24 — 1893, p. 651
— Wilson's Photographic Magazine, Volume 40 — 1903, p. 275