Using focal length in outdoor portraits

I read in the Digital Photography School blog a post about taking portraits out of doors and what to do about the back ground. A question the photographer might ask him/herself is, "how much background do I want in my frame? Do I want to concentrate on my model alone or do I want to show my model in an interesting setting somewhere?" (I'm using 'model' as a generic identification of the subject in your photo like a spouse, friend or relative.)

I took my oldest daughter, Lauren, to a lot with iron sculptures to demonstrate how the background disappears from the frame as I backed farther away from her and used my zoom to keep her the same size in the frame.

Here's a photo of Lauren I took from a few feet away and my lens set back to 18mm

As you can plainly see she is framed close and there is a lot of her and a lot of background in the photo. A close zoom like this might be used to show your model and where you are in the same frame without having your model appear too small and almost unrecognizable (something I see in so many tourist photos.)

In the next photo I've backed away from Lauren several feet and zoomed my lens to 95mm. Here you can see the background starting to disappear and she is the same size in the frame.

Last shot from several feet away and zoomed out to 200mm.

Here you can see the background has almost disappeared and the model still fills the frame. You can do this with almost any lens/camera that can zoom. If you're using a simple point and shoot you will want use the Landscape setting so the camera will use a small aperture and get the back ground in focus.