I normally use a 5D for much of my photography, but wanted something smaller and lighter for general travel photography, so I recently picked up an XSi and a Tamron 28-300 VC lens (also have a Rebel XT). I've noticed that many photos are out of focus when using the 9 point AF. If I use just manual center point auto focus the pictures are much better (AF Mode is set to One Shot & operating in Program Mode). I used it today on some product girls at a trade show and got the same result - slightly out of focus in 9 point mode, good focus in center point mode. Never had this problem with the Rebl XT or 5D. Any suggestions? Thanks!