Have several Tamron lenses along with the Tap-In and have done quite a bit of tuning. First thing to do is see if your lens needs tuning. Use the Tap-In to look at the tuning table. If it's a prime, there should be 3 distance entries and you will want to test at those 3 distances. If it's a zoom you will see a table of 3 distances and several different zoom factors. You will want to test each table entry. To see if your lens needs tuning, set up a target at one of the distances and take 3 or 4 pictures using AF through the viewfinder (uses phase detection AF) and 3 or 4 using Live View (used contrast detection AF). Use the sharpest in each set for comparison. Use a tripod, remote release, manual mode, raw. If they are about the same IQ, no tuning necessary. If the Live View shot is sharper, then you can benefit from tuning. Use the Tap-In to make the viewfinder and Live View images the same. It takes time and patience for a zoom, it's not too bad for a prime.