Yasin

I bought mine second hand and I played around with it but the day I took it outside for a trip to a forest/animal reserve I was frustrated with it, I thought I must be doing something wrong , but I kept getting terrible non sharp shots even though I tried different shutter speeds from 300 to 500 to 800 to even 1000 at different focal lengths, most times with fast aperture . After going home I did a fast sharpness test and realized it is sharp at around f8 to f11, it wasn't very good wide open at f4 or f5,6. I immediately put it for sale because I wasn't happy with it, but now I am wondering if it were just my copy or whether all copies are the same and I should not expect much from this lens .. : / the video of Christopher Frost shows it was sharp wide open from f4 till f11. what do you guys think ? this photo was shot at : 1/1000sec f5 iso 1250 at 165mm - xt30ii xf70-300mm