What is an F-Stop? Aperture Explained...

So,

You have been taking pictures for a while, and have always wondered what it actually means when people refer to an F-Stop... right?

The picture above is a great visualization as to what an F-stop can do to an image. The upper left hand corner is shot with an f-stop of f32, and the lower right hand corner with an f5. As you can see, depth of field is the most obvious thing that changes with an F-stop. Pictures taken with a lower F# tend to have only one subject in focus, and a higher f# will have more in focus. (more depth of field)

Now we have to tackle the problem of light. You will quickly notice that as soon as you adjust your f# to a higher number, your pictures will look exponentially darker... (There is something known as reciprocity that explains the relationship between exposure, ISO and F#.)

To combat this problem we must adjust the shutter speed in a corresponding mannner, and luckily for us, on 99% of the cameras out today, shutter speeds are arranged in a similar way, so that one step in the shutter speed scale corresponds to one stop in the F# scale.

So, have fun shooting!

(A rule of thumb for adjusting aperture manually is as follows: doubling the f-number increases the necessary exposure time by a factor of four.)