I recently purchased an a580 new and a used (2 year old; Ser. #3850202) CZ 16-80. This is my only lens. The lens looks to be "mint", the colors and sharpness are outstanding. The problem is (I think) it back focuses, i.e., the actual depth of field is from the focus point to well behind ...., never in front. I've checked it at all aperatures and the marked zoom settings and it is constant. I used Tim Jacksons "Focus Test Chart" and there appears to be a 20mm rearward shift in the depth of field, i.e., the chart is in focus 6mm in front of the focus point and 14mm behind the focus point. My questions are: 1. Could it possibly the camera? 2. If not, should I return the lens as defective? 3. Is this repairable ...., any idea what it would it cost? Thanks up front for any and all suggestions!