I talked with a nice Sigma rep and he gave me the option of sending the lens and camera in to them and they would adjust the lens to match the camera. I thought about this for a bit and decided against it. The main reason was the cost. I could send the lens back to B&H for no charge, or I could pay to ship the lens and camera to Sigma. With insurance this was going to run around $65, and I would not have the use of the camera for a week or so. So I sent the lens back to B&H. If I was near the Sigma service center bringing it in would have been the easy choice.
Rather than wait for another possibly defective lens to arrive at B&H and then get to me, I called Hunt’s Photo in Manchester NH. They had a lens shipped up from the Boston store. Today I went and briefly tested it out. AF seemed accurate at all distances. So I bought the lens.
I went for a walk around the village with it once I got home to test it out. I have only briefly looked at the pictures, but in going through them I feel the AF performance is acceptable even at f/1.4 and all the distances I tried. This weekend I’ll take a little more time to see if AF fine tuning will help, but at first glance it’s working fine without it.
When I started the walk I remembered the opening conversation I had with the Sigma rep. He initially thought I was calling to report an issue with the side AF points not working. I explained the issue with distances and he dropped the subject of the side AF points. This was also mentioned by another person in this thread I started on photo.net. In theory Sigma will have a fix for this soon.
So I also tested out the side AF points on a few shots. I think my results on this are inconclusive. Some of the shots seem off a bit using the side AF points, and a few seem OK. I will need to do a more controlled study. But for the time being I can live with just using the central point and recomposing. It’s still better than my results with manual focus and a fast lens on this camera.