Surplus Shed many years ago had a lens they believed was a Japanese Metrogon type, based on 3rd party information. They had no further info, other than someone's belief it was Japanese. I bought one & stored it. Surplus Shed still never learned anything more. I thought someone suggested it was a Fuji, but I try not to perpetuate that because I have never seen anything to support a particular company. Fuji is certainly a large company with a hand in many optics fields, but not the only lens maker. Consider that some US Metrogon's were made by a Zenith Optical company in West Virginia. I don't believe they were as large as Kodak or B&L, and started in a failed bottle manufacturing plant (with smarter people).
It's interesting in that it is a fixed, sealed assembly with a fixed, non-adjustable aperture and no shutter. The front diameter is considerably larger than the glass or contrast filters for the K-17 type 6" Metrogon (about 4" for the filter, which is wider than the lens). For the unidentified lens, the front diameter is about 5" or 5.5". The front filter has an ND central spot, so that suggests the lens is usable with other than black & white film.
Since it has a different form factor than the type of Metrogon used in K-17 shutters, it isn't necessarily made to MIL-STD150, and doesn't have to be 6" f/6.3, or even necessarily 9x9 or 8x10 negatives.
I saw someone else in Michigan describe a 12" Metrogon with photos that are of the same physical design as mine. But mine has a short projection distance of a ceiling lamp onto a wall that is closer to 6" (hard to estimate where the stop is when doing that).
The oddest thing about the lens is that the interior of the rear cell is painted bright white. Only thing I can think of is that white might have less heat absorption which could better control performance variation over temperature.
It's interesting in that it is a fixed, sealed assembly with a fixed, non-adjustable aperture and no shutter. The front diameter is considerably larger than the glass or contrast filters for the K-17 type 6" Metrogon (about 4" for the filter, which is wider than the lens). For the unidentified lens, the front diameter is about 5" or 5.5". The front filter has an ND central spot, so that suggests the lens is usable with other than black & white film.
Since it has a different form factor than the type of Metrogon used in K-17 shutters, it isn't necessarily made to MIL-STD150, and doesn't have to be 6" f/6.3, or even necessarily 9x9 or 8x10 negatives.
I saw someone else in Michigan describe a 12" Metrogon with photos that are of the same physical design as mine. But mine has a short projection distance of a ceiling lamp onto a wall that is closer to 6" (hard to estimate where the stop is when doing that).
The oddest thing about the lens is that the interior of the rear cell is painted bright white. Only thing I can think of is that white might have less heat absorption which could better control performance variation over temperature.
