I copy and paste my previous message in a proper thread that could be very useful for future users.
I'm helping my buddy with a Sony A7RIV + Sigma 15mm-MC-11 combo.
The camera become completely unstable.
It switches itself between AFS and AFC. Occasionally it focuses or the screen goes black.
The aperture does not work.
We initially tried with original fw and then updated camera and ring to the latest fw version
The sigma manual explains that if the ring led is off, the lens is not compatible and Sigma does not list the 15mm as a compatible lens but I trusted the many users here in the forum.
Given the so many references here for this lens, any suggestion?
At this point we will try the Metabones smart adapter V asap.
Is there some reason not to chose the Meta Smart Adapter IV over the V?
Thank you all