DAs Versus Kit

Lemmy

I would do some focus tests with your prime lenses first. My experience with auto focus is that every lens is slightly different. Many do not always achieve "perfect" focus first time. Some lenses will select a slightly different focus in consecutive tests. I use a split prism focus screen (as I manually focus a lot) so I know if the auto focus is correct or not. The smaller viewfinder on DSLRs make it difficult to evaluate focus yourself without one.

If after a number of tests you cannot get sharper images with the prime lens then I would suspect the lens is at fault and you should exchange it where you bought it.