A question I get a lot is what is aperture. Simply put, the aperture is the opening in the lens. The size of the opening in a camera lens regulates the amount of light passes through onto the film the moment the shutter is released. The aperture that you set (f/stop) impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light.
What Is Aperture And How Do I Control It
You'll often see aperture referred to as f/number or f/stop, for example, f/2.8, f/4, f/5.6, f/8, f/22, etc. Moving from one f/stop to the next doubles or halves the size of the amount of opening in your lens (the diaphragm) and the amount of light getting through.
If you shoot with natural light like I do, you can control the amount of light in your photograph by adjusting your aperture setting along with your ISO and shutter speed. The smaller the f/stop the more light you allow in, the larger the f/stop the less light you allow in.
Keep in mind, changing your shutter speed from one stop to the next doubles or halves the amount of light that gets as well. For example, if you increase one and decrease the other you will let the same amount of light you originally had.
Aperture and Shutter Speed.
Using a low f/stop means more light is entering the lens and therefore the shutter doesn't need to stay open as long, which translates into a faster shutter speed. Using a high f/stop means that less light is entering the lens and therefore the shutter will need to stay open a little longer, which translates into a slower shutter speed.
By using your in-camera histogram after you have set your aperture, you can choose the correct shutter speed for the environment you are photographing.
Aperture and Depth of Field
One important thing to remember here is that the size of the aperture has a direct impact on the depth of field (DOF), which is the area of the image that appears sharp.
For example the lower the f-stop, the larger the opening in the lens, the less depth of field, the blurrier the background. Whereas the higher the f-stop, the smaller the opening in the lens, the greater the depth of field, the sharper the background.
Choosing the Right Aperture
Now that we know how to control our lighting and depth of field, what determines the choices we make in selecting the aperture? While there are no rules, he is some quick guidelines.
For portrait photography, you will want to separate the subject from the surroundings using a focal point. Choosing a large aperture (lower f/stop, like f2.8) creates very shallow depth of field with only the subject, or just a portion of the subject, in focus, directing the viewer's attention to the subject.
In a landscape or scenic photography, you usually want to see as much detail as possible from foreground to background. To achieve the maximum depth of field, choose a small aperture (higher f/stop, like f/8 or f/11).
Now that you have an understanding of what is aperture and how to control it, you're one step closer to getting the perfect photograph in any lighting. Happy snapping!