I have a Canon 350D and a 75-300m lens.

When I first tried the lens at a Christening, I couldn't get it to Focus. Then I tried it when my son was playing football a couple of times and it seemed fine. Recently at a School play I tried to take some photos and it was out of focus again. It looks sharp as anything in the viewfinder but the results are very blurred. The only thing I could think of is the back focus is out, and this only shows up in the dark (as the focal point is different) and is fine in the brighter light...

Would this make sense? Or is it possibly the lens? All other lenses seem fine..!


Any help appreciated. I am tempted just to buy a 600D body. But would like to resolve this issue regardless.

Thanks.