Aperture


Lens opening. The hole or opening formed by the metal leaf diaphragm inside the lens or the opening in a camera lens through which light passes to expose the film.


Read this article Aperture

Read this article on Aperture

Article below is reprinted from Skip Henne Photography

The aperture is used primarily for controlling the exposure ( the lesson on Exposure follows this page, be patient) but it also controls the "depth of field" ("depth of sharpness" would have been a better term.
Words cannot explain this as well as visuals so take a look below at how different aperture settings can control the sharpness of objects in front of, and behind, the subject you are focusing on:
wideopen.JPG (6856 bytes)
wideopen.JPG (6856 bytes)

fEight.JPG (8388 bytes)
fEight.JPG (8388 bytes)

stopdown.JPG (7863 bytes)
stopdown.JPG (7863 bytes)

"Wide open" .. f2.8 to f4.5
"Optimum" .. f8 or f11
"Stopped down .... f16 to 32
If the lens aperture is "wide open" the depth of field is very shallow... notice how the runner (below) is sharp and the other players are out of focus

However, if you close the aperture all the way down objects in front of, and behind, will appear much sharper (see below).
duce td.jpg (25178 bytes)
duce td.jpg (25178 bytes)

By keeping the aperture wide open (left) we give the runner a "3D" look. He stands out among the out-of-focus players and our eye is drawn to him. If we close the aperture down (right) more objects are in focus and the runner gets lost in the crowd.
mcnabb V51.jpg (31566 bytes)
mcnabb V51.jpg (31566 bytes)

Therefore, if you have a camera that offers Manual Control, can use "depth of field" to help draw attention to the objects you consider important.
Now to some other tips lenses...........


Exposure

Please read this article on exposure and aperture http://www.andylim.com/photo/exposure.php