[stoppingdown]

Of course. Before doing that, I'd be curious to understand what the problem actually is. Because sharpness is ok, so it's not a matter of decentered elements. What could be that decenters vignetting but not sharpness? Also, while the problem is perfectly reproducible, in some bursts I see it happens with different intensity. But the only thing that changes in the burst is the shutter time. At first I even thought that was due to the shutter my a6300 (the oldest camera body), but the problem happens also with the newer cameras.