Camera Aperture Settings Explained
Its mechanism similiar to the iris of your eye, camera aperture settings work in direct conjunction with camera shutter settings to determine how much light enters an SLR’s body during a particular exposure. The larger the aperture, the greater the amount of light is allowed through the lense during a particular exposure. The smaller the aperture, the lesser the amount of light is allowed through the lense. If you liken the whole system to a water faucet, an SLR’s shutter will determine how long you turn on the water, while an SLR’s aperture settings will determine how wide you open the faucet.
Camera aperture settings are numbered, and this is often a point of confusion for new photographers. Contrary to what one might think, the smaller the aperture setting, the greater the amount of light is allowed into the camera. And conversely, then, the larger the aperture setting, the lesser the amount of light is allowed into the camera. So, for example, a camera aperture setting of f2.8 allows more light into a lense than would, say, a camera aperture setting of f11. You can see this in action if you take your SLR’s lense off your camera’s body and look at the body side of the lense. For this example I’m using a lense with an aperture range of f3.5 to f22.
With your lense in your hand and looking at the lense from the body side, slowly turn the lense’s aperture ring to its lowest number–here it’s f3.5. Take a look at Figure 1.
- Figure 1: An SLR lense dialed to an aperture setting of f3.5.
As you continue to turn the lense’s aperture ring and close down the aperture, you will see the aperture get smaller. Here in Figure 2, our lense is at f8–exactly halfway between being fully open and fully closed.
Figure 2: The same lense dialed to its midpoint f8.
Now slowly turn the lense’s aperture ring to its highest setting–here we’ll say f22. Look at Figure 3.
Figure 3: Here’s the same lense again “closed all the way down” to f22.
Now do it again and watch the aperture. If you look closely, you’ll see some metal sheets that open and close kind of like a super-villian’s helicopter-port roof. See how those sheets open and close? This mechanism is your lense’s aperture, and its degree of openess is described with the corresponding numbers on the aperture ring in terms of what is called “f-stop.” An aperture setting of 2.8 is called “f” 2.8, written f2.8. And you can see in the photos above how a smaller numeric aperture setting such as f3.5 would correspond to an actually larger value of the actual opening. This is because f-stop actually describes the change in the lense’s focal length, and we will discuss this–and how it affects what is called “depth of field,” later.
As photographers, when we talk about camera aperture settings, we say things like “the camera is opened up,” or the camera is closed “down.” If a particular photo was shot at f2.8, you might here someone say, “I shot this all the way open.” Or, again, “I opened all the way up.” If a photo were taken at f11, you might hear the same photographer say “I closed all the way down for this one.”
