Any ideas? Besides extension tubes?

The Tamron won't physically mount to the F mount.

Seems as though the BlackMagic aperture control ring makes contact with the lenses VC and AF/MF control switch area.

I can get it to set in place and slightly turn, but there is heavy resistance.

Anyone know the makeup of the F-mount adaptor and if it's worth shaving down that portion of the inner plastic ring to make room?

Kinda don't want to go the extension tube route to remedy this.