The basics of the aperture
The aperture is the opening in your lens. By making that opening larger or smaller, you control how much light comes through during the exposure. A small aperture is achieved by setting a high aperture number. For a large aperture, a big opening, thus more light, you need to use a small aperture value. So the higher the number, the smaller the aperture becomes. And the lower the number, the larger the aperture. Aperture is indicated with f-stops. Which aperture values you can choose depends on your lens. A fast lens, for example, has a maximum opening of f/1.8, while a zoom lens can have a maximum opening of f/4 or f/5.6.
Large aperture, low aperture number
Small aperture, high aperture number
What does aperture do to your photos?
Now you might understand a bit more about what aperture really is, but what does your aperture do for your photo? To truly understand this, you need to know what depth of field is. Depth of field is the area in front of and behind the point where you focus that is rendered sufficiently sharp. ‘Under otherwise equal conditions, a smaller aperture provides more depth of field. The focal length and the distance at which you focus also play a role.’ With a large aperture, so a small number like f/1.8, the background becomes blurry. A very small opening, such as f/22, can make fine details softer due to diffraction: light bends at the aperture opening. Therefore, the highest f-number does not automatically yield the sharpest photo.
Blurry background due to large aperture, low aperture number.
Foreground and background sharp due to small aperture, high aperture number.
What is bokeh?
We have talked about bokeh before, but what exactly is it and what does it have to do with your aperture? The word bokeh comes from the Japanese word for blur. In photography, it refers to the quality of the out-of-focus area in the photo and is related to depth of field. Bokeh describes how the blurry parts are rendered, for example soft and calm or busy. More blur does not automatically mean more beautiful bokeh.
F-number | Aperture opening | Amount of light | Depth of field |
|---|---|---|---|
Low, for example f/2.8 | Large | More light | Smaller: a smaller area is sharp |
Medium, for example f/5.6 | Medium | Less light than at f/2.8 | Larger than at f/2.8 |
High, for example f/11 | Small | Less light | Larger: more of the foreground and background can be sharp |
