Reply to Robert and David
In feathering the light, yes, you have the person the farthest away get the center of the beam and the person closest get the slightly less, feathered light. Therefore on the negative since the person that is father away from the light they will get approximately the same amount of light as the person closer who is getting the feathered light.
With a one light set up, which is perfectly fine for most portraits, you are better off to use a reflector on the shadow side to bounce back a bit of light. But feathering still creates a softer wrap around lighting effect. Also the feathering will aid in having light strike the reflector which will inturn bounce it back to the shadow side. The distance from the subject that you place the reflector is quite visible with your modelling lights on. So you can control whether you are getting a 3 to 1 or a 5 to 1 lighting ratio.
When discussing light we talk about QUANTITY of light and QUALITY of light. The quantity of light is the amount of light striking the subject. The quality of light is the kind of light striking the subject.
You can have a meter reading of say F8 on a subject using a six inch reflector on your light and also F8 on the subject using an umbrella or softbox on your light. They both have the same quantity of light but a very different quality of light. Feathering the light works for both.
Since I'm prattling on about lighting, a lot of people don't know that the closer the light is to the subject the softer it is. ( check the catchlights) Another quality of light issue. As for an umbrella vs a softbox both have close to the same quality of light but a softbox is more controllable and easier to feather. As well when feathering an umbrella you have to be careful not to flare your lens.
If you are new to lighting get a book on it and you can easily see how to light a face for a flattering effect. The use of a "broad light", "short light", "butterfly light", "split light", "3/4 light", can have a huge effect on the results of your portraits and all you really need is a light, softbox, and a reflector to do this. These lighting techniques can make long faces look shorter, broad faces look narrower etc and help you produce great portraits.
Hope this helps,