Does anyone have any information on the "C-Congo 1:6.3 f=180mm Yamaskaki Opt. Co." in a Seikosha SLV shutter? I believe it's the same lens as the Commercial Astragon 180mm f/6.3. I've seen pictures of both in the Seikosha SLV shutter and they look identical. Both seem to have been made by Yamasaki.
Some hints I've been able to find on the forum are here:
https://www.largeformatphotography.i...6-Congo-Lenses
https://www.largeformatphotography.i...-from-Yamasaki
There's very little information available on Yamasaki (Congo/Astragon) lenses in general, and this one in particular. I know it's a 4 element Tessar design. It's coated, likely single. But that's it. I've been told it covers 4x5 with very limited movements. I'm curious to know the image circle size and the weight of the lens. Thoughts on performance are welcome too.
Interestingly, the old Congo Lenses website from the late 1990s only lists a Commercial Congo 180mm f/6.8. There's no mention of an f/6.3 lens. The f/6.8 version had a big image circle of 220mm (presumably at f/22) and weighed a svelte 180g.
Congo website: https://web.archive.org/web/19981206...go/index_e.htm
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