Well, 18-200mm lens is a great all around lens. Unfortunately, it's not fast enough for kids. So I did some research and found that this 50mm lens is one of the best for portrait. It quadruples (did I write it correctly?) the ISO and gives a very sharp picture in a minimum light environment. And it's fast enough for my kid.
One thing is that it becomes a 75mm lens on my D40...but it's okay.
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I finally can take a great portrait picture of my daughter.
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Look at the bokeh...luving it!