Achieving a Blurry Background: The Power of a Small f-Stop Number

Achieving a Blurry Background: The Power of a Small f-Stop Number

In this blog post, we’ll explore what an aperture is, how it affects photographs, and how using a lens with a small f-stop number can help you achieve that beautiful blurry background.

Photography is an art form that allows us to capture moments in time, telling stories and evoking emotions through images. One of the most sought-after effects in photography is the blurry background, or bokeh, which helps to isolate the subject and create a pleasing aesthetic. Achieving this effect can be done by using a lens with a small f-stop number.

Understanding Aperture in a Photo Lens

The aperture of a camera lens is the opening through which light enters the camera. It is similar to the pupil of an eye, which expands and contracts to control the amount of light that passes through. The size of the aperture is measured in f-stops (or f-numbers), such as f/1.8, f/2.8, f/4, and so on. The f-stop number is calculated by dividing the focal length of the lens by the diameter of the aperture.

  • Small f-stop number (e.g., f/1.8, f/2.8): Indicates a larger aperture, allowing more light to enter the camera.
  • Large f-stop number (e.g., f/16, f/22): Indicates a smaller aperture, allowing less light to enter the camera.

How Aperture Affects Photographs

Aperture is a critical element in photography that influences several aspects of an image:

  1. Depth of Field:
  • A large aperture (small f-stop number) results in a shallow depth of field, meaning that only a small portion of the image is in focus while the rest is blurred. This is ideal for portraits and macrophotography, where isolating the subject from the background is desired.
  • A small aperture (large f-stop number) results in a deep depth of field, meaning that a larger portion of the image is in focus. This is useful for landscape photography, where you want both the foreground and background to be sharp.
  1. Exposure:
  • A larger aperture allows more light to hit the camera sensor, which is beneficial in low-light situations. However, it can also lead to overexposure in bright conditions if not properly managed.
  • A smaller aperture allows less light, which is helpful in bright conditions but can result in underexposure in low-light scenarios.
  1. Image Sharpness:
  • Lenses often have a “sweet spot” where they produce the sharpest images, typically around f/8 to f/11. However, for creative purposes, photographers typically use larger apertures to achieve specific effects, like bokeh.

Achieving a Blurry Background with a Small f-Stop Number

To achieve a blurry background, you’ll want to use a lens with a small f-stop number, such as f/1.8 or f/2.8. Here’s why:

  • Shallow Depth of Field: A small f-stop number creates a larger aperture, resulting in a shallow depth of field. This means that the subject in focus will be sharp, while the background will be beautifully blurred.
  • Subject Isolation: By blurring the background, the subject stands out more prominently, drawing the viewer’s attention directly to the subject.
  • Aesthetic Bokeh: A larger aperture often produces more aesthetically pleasing bokeh, with circular and soft out-of-focus highlights.
Practical Tips for Achieving Blurry Backgrounds
  1. Use a Lens with a Wide Maximum Aperture: Prime lenses, such as a 50mm f/1.8 or an 85mm f/1.4, are excellent choices for achieving shallow depth of field.
  2. Get Close to Your Subject: The closer you are to your subject, the shallower the depth of field will be, enhancing the blurriness of the background.
  3. Increase the Distance Between Subject and Background: The further away the background is from the subject, the more blurred it will appear.
  4. Choose a Suitable Background: A background with lights or textured elements can create beautiful bokeh when blurred.


In conclusion, using a lens with a small f-stop number is a powerful technique for achieving a blurry background in your photographs. By understanding the role of aperture and how it affects depth of field and exposure, you can harness this knowledge to create stunning images that highlight your subject and add an artistic touch to your photography. Experiment with different apertures and distances to see how they transform your photos, and soon you’ll be mastering the art of beautiful bokeh.

Written by AI. Photo by Wan San Yip on Unsplash.