Hello. I've just purchased a Bausch & Lomb - Zeiss Unar series Ib 6.5x8.5, SN 772151 Pat 1900 (just Unar, not Portrait Unar). The aperture scale is strange. It marks 1.9 2 4 8 16 32 64. I go to google but there is less information. Just a few from wiki:
Anyone please let me know more about this lens. Thanks for reading.Probably inspired by the Stigmatic lenses designed by Hugh Aldis for Dallmeyer of London, Rudolph designed a new asymmetrical lens with four thin elements, the Unar Series Ib, with apertures up to f/4.5. Due to its high speed it was used extensively on hand cameras.
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