Canon FD aperture issue on Sony E mount adapter

Dear All,

I need your help on solving one issue with a Canon nFD 20mm f2.8 i have bought last week.

After connecting it with my adapter for E mount sony a7 (I am using the same for a FD 100-300 lens without any problem) I noticed that the aperture is working only from F11 to F22; first thing i have attempted was to push the two pin and turn clockwise the lens mechanism and i have noticed that the aperture is working without any problem while keep pushing the little metal wing (also if i keep the metal wing to the right with a finger I am able to change the aperture with the aperture ring).

When i turn back the mechanism anticlockwise and back in the normal position (red dot at 12 hour) the aperture is only working from F11 to F22. One more thing if i don't keep push the metal wing to the right when turn anticlockwise the aperture is stuck to F11 and will not change.

I don't think is an issue with the adapter, as i wrote i am using the same adapter on another nFD and i never had issue.

Any idea how to fix this issue, i talked with the shop that sold the lens and he told me that he doesn't know and that maybe i should try with an analog canon to fix it.

Thank you in advance for your help :)

Andrea

Does your adapter have an "open/close" or "lock/unlock" switch? Do you set this switch to the proper position before attaching it to the lens and do you engage it afterwards?

Can you maybe post a pictures of the adapter attached to the lens and the lens set to f/2.8 and F/22? View from behind into the rear of the lens.