Possible switch from Nikon

[jdh313]

I've tested it on a d40 as well and have the same issue, so it must be the lens. I'm still getting some sample images together (for the third time). Thanks for all of the help!
So back to Pentax...if I were to switch would the K50 or K5II be closer to my D7000?

 

[AceCo55]

Maybe something to consider ... based on my experience.
I started off with Pentax cameras and Sigma lenses. Very happy with the cameras.

What killed it for me was the lack of availability of Pentax mounts for the latest lenses.
I concentrate on sports photography, and I think I had to wait well over 12 months for a Sigma 70-200 with a Pentax mount.
Killed me watching what nikon and canon users could buy and use.

I also wanted a faster long lens,so the two issues took me away from Pentax to Nikon.
You may have different set of circumstances that negate everything I have said.

I wish you well - that lens is not working correctly and I feel you are entitled to a new replacement one.
Keep at them and escalate ... escalate.