HOW APERTURE WORKS

What is Aperture?

Aperture is a diaphragm like openig inside the lens which diameter is adjustable. By adjusting the diameter of the opening it controls the amount of light that passing through the lens and hits the camera sensor. However that needs to be balanced with a correct ISO setting (say ISO 100) and the right Shutter speed to get proper Exposure. Usually when a photographer sets the camera on aperture priority mode, the shutter speed and the ISO settings are auto adjusted by the camera.

Aperture is measured in F stops. Usually when you read the specifications of a lens you will notice a specification f/1.2, f/1.4, f/1.8, f/2, f/2.4, f/2.8, f/4 and so on. This is the measurement of the maximum opening of the lens. The more the number following the letter F, the narrower is the aperture (this is a bit confusing). Wider the aperture the more light it can take in and that means the less time the camera lens needs to remain open. As such wider the maximum aperture faster is the lens. When one shifts from one f/1.2 to f/1.4 or so on, the aperture of the lens is reduced by a factor of 2. The shutter speed as such needs to be increased by a factor of 2 to match the lack of light entering the lens. As such increasing one and reducing the other or vice versa will have the same effect.

Both wider and narrower apertures have their own advantages. The former is used to create a soft blur around the focus point (or the subject) which is also known as bokeh and the later is used for increasing Depth of Field and is generally used for the purpose of landscape photography.

Here are a few things to remember:
Smaller f number = bigger opening = more light in sensor = shallow Depth of Field
Larger f number = smaller opening = less light in sensor = deep Depth of field

There are several things you can accomplish by manually adjusting fstop. You can choose what “depth of field” you want by adjusting fstop. Depth of field means the amount of focus you want in your photograph. A photo with a “deep” depth of field means that the whole photo is focused. A photo with a “shallow” depth of field means that only a certain area of the photo is focused and the other areas are sort of blurred.

If you want your viewers to focus on a certain object in your photograph, you would choose a shallow depth of field because the object will be focused and the background will be blurry. This will force the viewer to focus on your object.

If you want your viewer to focus on the whole photo, you would need a deep depth of field. Nothing on the photo is blurred. Everything will be focused. This is great if you’re taking a picture of the landscape and you want your viewer to appreciate everything in your photo.

Take your time to discover the different aperture settings your camera has. The more you practice, the more control you will have over your camera.