why my jupiter 12 can't fit with my zorki 4

[heronop2003]

i just got jupiter 69xxxx so i try with my zorki 4 it not fit with it so i try with anotherone is also can't fit with that why?

and i try with canon P also can not fit it
how can i do ?

(but lens it fit with feb 3b that came with it)

 

[captainslack]

Can the J-12 even be mounted on the Canon P without it impacting the shutter?

 

[FrankS]

On the JUpiter 12 35mm lens the rear element sticks out way far (past the focussing cam) and jams against the light baffles just ahead of the film gate. The rear element comes very close but does not touch the shutter, the problem is the diameter of the protruding rear element. Some cameras don't have light baffles to interfere with this lens, some do.