Aperture (f-stops)

What is aperture?

If you search the definition of aperture in Google, you will get ‘an opening, hole or gap’. Yeah, aperture is a hole that allows light passes through into the camera body. The aperture is also known as f-numbers or f-stops. Different lens may give you different range of f-stops. 

Aperture Range

The diagram above shows the size of the aperture in different f-stops. The f-stops also impact the depth of field. Large aperture or small f-stop will make the foreground sharp but the background blurry. On the other hand, small aperture or large f-stop will make the foreground and background in focus. Below are the examples taken with different f-stops. 

Canon 600D @ 21mm, f/3.5, 1/50 sec, ISO-100

Canon 600D @ 21mm, f/9, 1/8 sec, ISO-100

Canon 600D @ 21mm, f/16, 1/2 sec, ISO-100

Canon 600D @ 21mm, f/22, 0.8 sec, ISO-100

From the examples, you can see that with aperture f/3.5, the background is blurry. As the aperture gets smaller (larger f-stop), the background gets sharper. 

What f-stop to use?

Here are a few senarios that you may want to take into consideration when choosing suitable f-stop. 

Low light condition

Small f-stop allows more light entering the camera, in other words, for low light condition, you may want to use lower f to get the shot done.

Bokeh

Small f-stop will help you to get a particular area in focus while the rest blurry. More info on bokeh.

Landscape 

In landscape photography, you may want to use larger f-stop to get sharp and focus background.

Night photography

You may have seen the lights in night photograph show star effect and wonder how to do it. With large f-stop, you may get this effect. More info on star effect.