Values for the aperture are written as a fraction, like this:<\/p>\n
f\/1 (Large aperture; lets in a lot of light)
\nf\/1.4
\nf\/2.0
\nf\/2.8
\nf\/4
\nf\/5.6
\nf\/8
\nf\/11
\nf\/16 (Small aperture; lets in only a little light)<\/p>\n
The aperture can be any value.\u00a0 But in practice, these values are the most common ones that are quoted.\u00a0 Moreover, these are the values used by lens manufacturers to represent the \u201cstops\u201d.<\/p>\n
Notice that the number is in the denominator of a fraction.\u00a0 Thus, f\/2 is bigger than f\/4.\u00a0 (In fact, it is two stops bigger.)<\/p>\n
A lens that has a large aperture (a small number) is referred to as a \u201cfast\u201d lens.\u00a0 In practice, numbers larger than f\/4 are \u201cfast\u201d and smaller than f\/8 are \u201cslow\u201d.\u00a0 It is likely that these terms relate back to the shutter speed: a \u201cfast lens\u201d lets you use a fast shutter speed.<\/p>\n
Unfortunately, most cameras show the denominator of this fraction as the aperture value.\u00a0 But remember that the aperture called \u201c2.8\u201d is still bigger than the aperture called \u201c4\u201d (because it is really \u201c1\/2.8\u201d versus \u201c1\/4\u201d.<\/p>\n