I bought my 550d with the twinkit just over 2 months ago and when I use the 55-250 I find that I have to manual focus, but with the 18-55 the auto focus works fine. At first I thought maybe it was because the objects I was trying to focus on were too close and the was confused but I have just been outside testing it on objects further away and it just can't auto focus. A couple of times after taking a shot on manual focus, I switched it to auto and it worked ok but then as soon I tried to take a shot of something else it wouldn't work. Is there something I am doing wrong??? Or is there something wrong with the or is it a fault with the camera. I am thinking I will have to take it back to the camera shop but just wanted to check here first. Any help is appreciated.