I'm thinking of sending it my 17-50 f2.8 VC lens as I think the focus is off as the images seem very soft esp. at 2.8. (totally unusable) Anyone ever deal with Tamron support? Any suggestions? If it turns out that the lens is within spec, whats your thoughts on the Nikon 17-55 f2.8? What do you think is a fair trade in value of the Tamron?