f/Stop and Aperture - Opening your in-camera Eye

Your aperture is designated by a meter of numbers - the f/stop. You'll see in your camera (when you set it to manual mode or aperture priority mode) that the f/stop is designated as a number -i.e. F 5.6.

Now that we know where on the camera to find this magical number sequence, what does it do? Aperture defines how much light is hitting your sensor at any given shutter speed. The higher the number beside that F goes, the less light per shutter click is hitting your sensor. Why would we want less light hitting our sensor you may ask. The less light available to our sensor at a given time, means the longer the exposure time must be to get the correct exposure. Thereby slowing down all action that is happening in the frame. However, not only does it reduce the amount of light coming in via your lens, but the higher the f/stop, the larger your depth of field is.

The higher your f/stop number, the larger amount of your frame will be in focus -increasing your available depth of field. If you want a shorter depth of field, use a smaller f/stop.

Okay, so we've covered depth of field and how light affects our exposure time. How do we use the aperture control to our benefit?

Using the f/stop effects combined with our shutter speed gives us a level of control and flexibility far greater than the use of one setting alone. We now have the knowledge and ability to control many aspects of our image: how much is in focus, how much action is captured, and how much exposure to light it has.

There are other ways of controlling aperture, such as with extension tubes or filters. Generally with the addition of aperture alterring elements, the overall speed of capture will be slowed by a stop or two.