John Deerfield , Jun 16, 2011; 09:25 p.m.
I might suggest learning about photography including lighting. We certainly can't teach you everything in a forum thread. Simply owning a camera and lens doesn't a photographer make anymore than owning Excel makes one an accountant: it is you knowledge that matters. The best lens to use is the one that will deliver the results you want. I saw a photographer using a 70-200mm lens with an extension tube so they could get in close and get a really shallow DoF. So it depends on the look you want. There isn't a "newborn" setting on the camera. Your lighting gives you a certain EV from which you have to make decisions, again based on how you want the image to look. A very important part of portrait photography is controlling the contrast. This means learning lighting. You camera doesn't control the contrast. It merely records it! Think of a voice recorder: it tapes your voice. Maybe you have a radio voice, maybe you don't. It isn't the tape recorders job to make your voice something different. It isn't the cameras job to control the lighting/contrast, only to record it.