What Does f/1.8 Mean on a Lens?

As an Amazon Associate we earn from qualifying purchases.

Every lens comes with a certain specification which allows us to know what it can be used for. Usually, there are two numbers in the title, each specifying a certain quality. Before making the purchase, it is important to know what f/1.8 means on a lens.

What Does f/1.8 Mean on a Lens?

F/1.8 describes the ratio of the aperture to the focal length of the lens. F/1.8 also implies that it is a wide aperture and will allow more light to enter the camera. Thus, it will be able to capture better images in lowlight conditions.

F/1.8 camera lens

What Is Aperture?

Aperture refers to the opening through which light enters a camera. Aperture allows you to control the depth of field, and through that, you can add dimensions to your images. An aperture around the f/1.2 to f/2.8 would be known as a wide aperture while an aperture around f/4 would be a narrow one. 

Wide apertures allow you to capture blurred backgrounds with a shallow depth of field. They are good for capturing Bokeh effects. On the contrary, a narrow aperture would give you sharp areas on every part of the image and this is good for capturing landscapes.

Moreover, the wideness of an aperture impacts the exposure of a photograph. A wide aperture lets in more light and is thus ideal for low light conditions. On the contrary, a narrow aperture is not ideal for these conditions.

What Can You Capture With an f/1.8 Aperture?

An f/1.8 is known as a ‘fast’ aperture and can be paired up with other settings such as shutter speed, and ISO level to capture a wide range of effects. The f/1.8 aperture lenses are usually used for portraits, bokeh, and low light conditions.


A wide aperture such as f/1.8 allows you to blur the background, focus on the subject and thus create a beautiful Bokeh. This makes for good portrait images whether indoor or outdoor. It makes sure that the subject is separated from the background. 

If it is paired with a high resolution (above 20 megapixels) camera, it can get you very detailed portrait images and can be used for fashion and product photography too.

Follow these steps to capture a great Bokeh:

  1. Increase the distance between the subject and the background. 
  2. Use a backlight or a hair light to create highlights in the background.
  3. Focus on the subject and capture the image.
Canon camera with a f/1.8 camera lens

Low Light Conditions

You can use an f/1.8 aperture lens in low-light settings to capture focused and clear images. This is because a wide aperture such as this captures more light and thus you can keep your shutter speeds below 1/200 seconds to avoid motion blurs.

Also, with a wide aperture, you can keep the ISO levels on your camera below 500 to reduce noise in your photos. This makes the f/1.8 great for indoor photography such as church weddings, and architectural shots.

In addition, star photography can be done with wide apertures too. Here, you can keep the ISO levels as high as possible (most cameras offer up to 25600) and slow shutter speed (above 10 seconds) to capture as much light as possible.

Related Questions

Is f/1.8 or f/2.2 Better for Photography?

There are not a lot of differences between these two because both are wide apertures. However, f/2.2 is considered lighter, smaller, and low-priced. On the other hand, the f/1.8 can let in a lot of light and perform better in low light conditions. Thus, it depends on the situation at hand.

Are Narrow or Wide Apertures Better?

While a wide aperture is better for portraits, Bokeh, and low light conditions, a narrow aperture will be sought by photographers who want to capture landscapes and architectural photographers thanks to its overall sharpness.

Thus, there is no absolute answer here. It depends on what you are trying to capture.


The f/1.8 on a lens depicts the ratio between the aperture and the focal length. f/1.8 aperture lenses are wide apertures and can be used in low light conditions, portrait photography, and for Bokeh.