What is aperture?
The aperture is the variable opening of the camera lens and
controls the amount of light that strikes
the film or censor. Each variation is referred to as an
Imagine the aperture of the lens is like a tap. The more
you open a tap the more water pours through it. The more
you open the lens aperture the more light pours through it.
Remember, the shutter speed controls how long light is
exposed to the film or censor, the aperture controls how
Like the shutter speed, each 'stop' is half or double the
Common f -stops are:
f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22
<-- wider............narrower -->
Modern cameras may also have increments between the above
The aperture is used to control depth of field (Dof). An
in-depth explanation of Dof can be found here, but in
a nut shell, the wider the aperture the narrower the
Dof. And conversely the narrower the aperture the
greater the Dof.
The iris of your eye behaves in the same way as the
aperture of a camera lens. Generally, our eyes are about an
f/8 in terms of Dof.
The aperture and shutter speed are used in conjunction to
obtain a correct exposure. Usually you decide what you're
going to photography and make the settings accordingly. For
instance, if you're photographing motor sports, your
primary thought will most likely be sharp images of
vehicles so shutter speed will dictate your game. If you're
photographing landscape type images then aperture will the
controlling factor. Likewise, if you're hand holding the
camera, you'll need to be conscious of shutter speed to
prevent camera shake.