If you want to take truely great shots, you are going to have to become familiar and comfortable with both aperture priority and shutter priority shooting. Today we're going to deal with aperature priority and the fstop.
On almost every camera I've owned, aperature priority is indicated by an A or an AV on the shooting mode dial. I could give you a long song and dance about why it works the way it does, which is confusing in the extreme. So, I'm not going to do that. Instead, I want you to think about the F in Fstop as meaning focus, as in what do I want to be in focus in my picture. The smaller the f number, the shallower the depth of field, or, your subject will be in focus, but the background won't. The higher the fnumber, the more of your background will be in focus.
To see for yourselves, how this works, I'd like you to try this exercise. You'll need a fence and three bottles or cans. Place your cans/bottles approximately ten feet apart on the fence posts. Position yourself about four feet from the first can. Turn your shooting mode dial to A or AV and select the lowest fstop your camera offers, focus on the first can and shoot. Once your in A or AV mode turning the wheel will select the fstops. Next I want you to select the fstop in the middle somewhere around 5 or 6 focus and shoot. Fineally select the largest number your camera offers, focus and shoot. When you look at your shots on the computer, you will understand what the fstops do. Next week, we'll go into what fstop for what situation.
PS: Those of you with the Nikon P80 who have been taking pictures where the subject is so dark you can't tell who or what it is. In your playback menu, select D lighting and see what happens.