Trying to decide on a lens to purchase for a D5200. Was thinking of the 24-120mm f4 lens but that was just recently not favored in a separate thread. Also thinking of possibly the Sigma 17-70mm. I currently have the 17-50 and have been very happy with it and thought the extra range might be nice. This camera and lens will be used by my teenager. She does a good deal of her school yearbook shots. Often she prefers to stand back and get shots of the natural action happening around her, hence a little range would be nice. Often times when she is borrowing she goes for the 85mm and that is used on a crop sensor. Would also like the lens to be a little durable. Think, on and off buses, field trips, dances, etc.