I am debating on purchasing a lens. There are two that intrest me but I'm not sure wich one would be better for portraits. One is a Sigma its zoom range 20-44. It has been digitally enhanced and the f-stop is lower then the Nikon I think it is 2.5 or so. The Nikon lens has a zoom range of 24-120. It has vibration reduction and the f-stop is 3.5-5.6. I am not sure wich one would be better and the price diffrence is only $50.00. Any ideas?