After some struggling, I conclude the dimension which indicated ‘a’ and ‘b’ above is slightly different and made the problem.
‘a’ is the distance from lens flange to bayonet blade of ULATA adapter.
‘b’ is the distance of same from original Sony 28-70 lens.
I could not measure precisely due to lack of tools but it looks a < b with eye. It is small difference, but the fact is A7, A7R, A7s have plastic ring
in between lens mount and body. So even with slightly incorrect adapter, applying a little more force will turn the adapter to fit.
At A7m2, the plastics ring replaced with metal. So lens mount rigidity increased but no flexibility as all as before.
If adapter dimension is slightly smaller than spec, it won’t turn.
I received long waiting FD adapter for Canon FD 85mm f1.2 Aspherical lens.
But OMG….it won’t fit to camera
This is nice looking ULATA adapter from China….
Attached to the lens.
Disappointingly it refuse to connect to Camera body
This is grand parent of famed ‘Mantou’ lens, Canon EF 85mm f1.2 L.
It started as FD mount 85mm f1.2 Aspherical as shown below.
I shot this with 85mm lens handheld without fixing to the body. Wow….such a shallow DOF
This is a DOF from Mitakon