I bought my Nikon d3100 last year and I really like it, I've taken some pictures with it and they've come out amazing! But I wanted to take videos on it, I'm still not really sure how to fully use it but I have the 18-55 mm lens that came with it and I dont know if it can auto focus during a video? Like I wanted to show things close up and make it auto focus automatically.. Is it able to do this? I dont really know much about it still so I'm still looking up how to use it. If it can't do this is there a special lens for it that will make it auto focus in a video? Thanks for the help 