Mukul Dube , Dec 17, 2013; 12:33 a.m.
Brandy, a spot meter reads light only from a small, defined area. It has a narrow field. In general, several readings are taken and then combined (a "weighted average"). For portrait work you will probably be better off with an incident light meter. If you have only the spot meter, place a piece of white card or paper in the same light as your subject, take a reading off that, and open up the lens two and a half stops more than the indicated value (or adjust shutter speed to get the same exposure). Film speed must be set on the meter beforehand.