http://www.nikonchat.com/af-s-nikkor-50mm-1-8g/

Nikon 18-70mm f / 1.8 G or 35?
I started a small home studio, and owner of a D5000, for now, also a Nikkor AF 50mm f / 1.8 G-55kit a lens 18, and I'm looking at to achieve a goal more for kids and especially portraits. I like my 50 mm is a very good goal allows a large amount of light, but it is not autofocus on my D5000. So I need some help choosing what is best for my needs? I should stay with me or get a 50mm AF-S 35? thanks
One of the things you are looking for a goal to do in the portrait photography is that the separate subject background. In general, the theme is nice and clear and the bottom is soft out of focus. Attractive for soft focus, you need a lens that has good "bokeh." The Tamron SP 90mm is famous for this, but I'm not sure how much space you have in your home studio. Many people are using a 70-300, closer to the end of 70 mm for a similar result. You should not take portraits with any lens of 50 mm shorter than that of a cropped image sensor as the D5000 as they tend to make the subject look fatter. If you are looking for the best image quality, a rule of thumb is to stick with prime lenses, 50 mm is a great example, Nikon 60mm Micro, Nikon 85mm zoom or the Tamron 90. To more versatility and if your study is too small might be a better way to go. It is easier if your shooting singles or in small groups. I'd lose 18 to 55 and go to any of the Nikon 16-85 or try the new version of the Sigma 17-70 f2.8-4 macro.