I use a 70-300 zoom lens with various filters (softener, polarizer, orange et.al.) for portraits (both inside with flash-heads and outdoors and a Canon EF 50 mm f/1.8 as well, but you need to get close to the face which can be intimidating. But I am saving up for a Canon EF 85 mm, f/1.8 (was suggested to me by Cheryl).
Originally Posted by Nicole McGrade
For your Hasselblad, a Carl Zeiss 150 mm, is a GREAT choice for portraits.
For all lenses for this purpose it's important that they are fast, as a wide aperture will help you to blur the background and keep the person pin sharp at the same time.
See this thread for more info (I know it is 'bout Canon lenses, but the main idea could be of interest for you. Nikon must be having a similar lens):