Still playing with my new lens, and decided to try a focus stack with the Combinezm software. Came out fairly decent, but I didn't quite get the front and back of the coin, and there is some artifact on the right side. Tell me what you think and how I can improve.

I was in the house, and grabbed what i had. I didn't use a rail, with the camera on a tripod, I set my lens to minimum focusing distance, positioned the nickel for the front edge, then gradually changed focus point with focus ring.
