Before being moved downstairs to the ground floor, we were told that photography would not be allowed during the rest of the tour. We were also warned that the factory floor might be coated with lubricant, and it was, but this was okay, this is a factory right? We were led into a corridor, where a dozen technicians were busy working with dozens of custom designed end-milling machines. Our guide took us into one of the rooms where lettering was being engraved into aperture rings for what appeared to be for a Voigtlander f/0.95 lens. We were able to handle the rings, but unfortunately we were not able to take any as souvenirs. Our guide told us that it can take up to 5 minutes to process one ring, where the normal silkscreen printing that other manufacturers use, takes less than 5 seconds per piece.
We were led into another room that was milling Nikon F-mounts out of a large hunks of brass. We were allowed to hold the pieces for a close-up look and they had a very nice weight, and were beautifully machined.
Next, we were led into a room where a technician was working next to a table with dozens of anodized inner and outer focus helicoids. We watched, as he painted on a grey compound and worked a pair of barrels back and forth. Focus helicoids are made with threads that use higher precision than normal screw threads, but still, there can be tiny differences in the matched parts. This could result in a small changes in resistance, that may be detected by the user's touch. It's the technician's job to use his years of experience, in this case 40 years' of experience, to turn the mating parts back and forth, until the parts have the perfect silky smooth action, not too tight, and not too loose. We are talking about precision, not in millimeters, but in microns. Each helicoid pair is unique and it can take anywhere from 4 to 40 turns, to get it just right, the technician told us. At Cosina, every lens that leaves the factory with the focus helicoids lapped by a master craftsman before final assembly.
The tour really opened my eyes to the impressive work that Cosina does. Unlike Zeiss, Leica, Nikon, Canon, or almost any other brand, Cosina still makes their own glass, makes the entire lens, start to finish, including all of the parts, down to the fasteners using their own designs. Unlike Canon, Nikon and Sony, all Cosina manufacturing takes in Japan.
Cosina has remained under-the-radar over the years, avoiding attention to their main business, which is OEM manufacturing. While most lens brands advertise their skills at making lenses only to outsource the manufacturing, Cosina has been quietly making high-end lenses for these companies over the years. These high-end lenses are made using much tighter tolerances and fit than the mass produced motorized AF lenses made by other brands.
Cosina has been active lately with new designs in their own APO-Lanthar line with the new Voigtlander Apo- Lanthar 65 mm f/2 Aspherical 1:2 Macro lens for Sony E-mount. A detailed review and image quality test of the Apo-Lanthar 65 will be available here https://www.closeuphotography.com/voigtlander-apo-lanthar-65-mm-f2-macro-lens-test/on Closeuphotography.com (this page will be updated soon with much more information)
At the CP+ show in Japan in March 2018, Voigtländer announced three new lenses for Sony E-mount, including very interesting Voigtländer Macro APO-Lanthar 110mm f/2.5! It's great to see Cosina getting back to producing new Voigtlander macro lenses as they did in the old days, before they started manufacturing the ZE and ZF lens line for Zeiss.
The Cosina Voigtlander lenses are known for high-end image quality and superb build quality, but these are not the only factors that make these lenses so attractive. These high-end lenses are realistically priced at a level that an average photographer can afford.
I hope you enjoyed this brief recap of our factory tour as much as I enjoyed taking it. On behalf of myself and my photo group I'd like to sincerely thank Mr Yamada-san and the Cosina staff for making it possible and for the time they spent with us.
For more information on Cosina, and Voigtlander:
The Cosina Voigtlander and Zeiss lens lines: