Hi. I recently purchased in of these lens from B&H in New York and have noticed some weird focusing behaviour. It is paired with my k3ii.

When I try to take photos at 300mm it won't focus at infinity either on auto or when using the manual focus ring. If you back it off to 280 ish it seems to work or if I try a shot a bit closer it comes into focus. When I was checking my photos the exif data says the lens is at 260 even though on the Barrel it is definitely 300.

I did a bit of an experiment and it at 55 it's ok but gradually the error gets bigger through the range. It also makes a rumbling noise like the plm motor is constantly focusing but the image doesn't change and it does it even in manual focus mode.

Not sure if the lens is faulty so any feedback is appreciated. I am in New Zealand so limited support down here.