I own three Jupiter-8 lenses, two for the Kiev and one for the M39 mount. All three are soft wide open , but very sharp when stopped down. The stepped aperture of the Kiev-lenses are easier to use than the stepless one of the M39 lens.
The little wooden piece under the infinity lock makes the distance setting less frustrating.
The Zorki 1 with the J-8, an Altix 35/50mm finder and a selfmade handgrip.