I am just testing my 2 year old Panasonic 20/1.7, because sometimes the AF is out of focus. Test environment: Center (small) focus field, no eye detection, high contrast subject within the focus field, not very bright (inside room conditions), using tripod for constant results. It might happen that I focus 30x and everything looks good (e.g. when checking by the magnification). Then the next 30x (same unchanged condition) the AF also tells me 'success' (by this beeping noise), but the result is completely (not only slightly) out of focus. What's the reason for 'indicating success', but beeing completely out of focus?