F-stop Comparison -- Plant in a Hotel Lobby

When beginners/amateurs (like me!) hear about 'setting your F-stop', we think that you are speaking a foreign language to us that we will never understand! (We want to run back to the 'automatic' setting on our cameras....)

The simplest explanation (that has stuck with me) of how an F-stop works is to think of a line of ten people. They are standing in line in front of your camera, each waiting his turn to get his picture taken.

If you take a picture of this line of people at a low F-stop (example: f/1.8), only the first couple of people who are closest to the camera will be in focus; the rest will be blurry.

As you increase the F-stop, more and more people will be in focus. A high number F-stop (example: f/22) will not only get the whole line of ten people in focus, but probably most of the background as well.

Why wouldn't you want everything to be sharply in focus? I suppose, it depends on the 'focus' of your picture. If you want to capture all of the details in a particular scene, then you would want to set your F-stop out to something higher (higher than f/1.8, although you may not necessarily need to go out as high as f/22). If there is really only one element that you want to be the 'center of attention' in your picture (you only want to catch a picture of that first person in line), then you would set your F-stop lower (to something like f/1.8).

Another reason that you wouldn't want to shoot at your highest F-stop is that high F-stop pictures will take longer than those where the camera is set to a lower F-stop setting. Depending on how much light is available to you, a higher F-stop might take you beyond 'hand-held' ability and into the realm of needing a tripod (or other stationary mount for your camera).

Here are two HDR compositions built from two sets of photos that I took in a hotel lobby; the first set was shot with an F-stop of f/1.8, the second f/22. I liked this plant well enough to sit and shoot 50 pictures of it with a remote control and my Sony NEX-7 (mounted on a tripod). You'll notice in the first picture (f/1.8) that the plant is in focus, while the background (the stocking on the fireplace, the tree and lamp) are blurred. While the background items are in-focus in the second picture (f/22), I'm actually fonder of the first. What are your thoughts?