Did you ever figure this out? I just bought this lens and no matter how much I turn the outer focus ring, the image is completely blurry / pixelated. There is the knob that unscrews on the inner ring’s side, but I’m not sure what this does. I can’t find any user manual either.
Well, I found a solution, no clue if it’s the correct one. You should try to unscrewing the whole lens while watching the live feed. At some point you will get a clear image. To be able to firmly screw the lens into the camera at the right distance, I 3D printed a small ring that I inserted between the camera and the lens.