Great purchase. Sometimes the auto focus wouldn't just focus in certain light situations. It would focus than unfosus multiple time and never get it a focus (makes a racket continually trying to focus but doesnt). You have to go manual when that happens. Normally the focus works great. I'm not an expert but I think it is normal for that to happen when light situations makes it hard for the camera to knew which thing it should be focusing on. Still an excellent lens and a more experienced user this focus issue wouldn't be a big deal. Worth the cost and worked great otherwise. It just took a while for me to learn to use it properly.