General
How an aperture works – Camera lens aperture explained simply
Aperture is one of three key parameters that influence how much light enters your camera. This blog will dive deep into what aperture is, how it works and its usage in photography.
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What aperture is and how it works
What are f-stops?
How an aperture affects photos
Aperture on different lenses
When to use what aperture
How to set an aperture on the camera
What is an aperture in photography?
Aperture is the opening in a camera lens through which light passes to enter the camera. It functions similarly to the pupil of an eye—adjusting to control the amount of light reaching the camera sensor.
In the camera, the aperture setting allows for control over how much light enters the lens. You can set it manually or rely on the camera to select it for the photo.
How an aperture works
When shooting in low light, the aperture blades open wide to let in more light. In bright sunlight, the aperture blades close more leaving just a narrow hole to prevent too much light going inside the lens. This is exactly the way the pupil adjusts to the light.
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What are f-stops on the camera?
F-stops, or f-numbers (e.g. f/16, f/8..), are the standard units used to measure the size of the aperture opening in a camera lens. The "f" stands for the focal length of the lens, and the "stop" refers to the adjustable settings on the lens aperture.
The f-stop value is basically the ratio of the lens's focal length to the diameter of the aperture opening. For example, for a lens of 50mm if the aperture diameter is 25mm the f-stop will be 50 mm/25 mm= f/2.
F-stops are typically expressed in sequence: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, and so on. Each step up the scale (increasing the f-number) halves the light entering the lens, while each step down (decreasing the f-number) doubles the light.
- The lower f-stop – the wider the aperture is – the more light goes in
- The higher f-stop – the smaller the aperture is – the less light goes
How aperture affects photos
Aperture affects the exposure
Exposure determines how light or dark an image appears. Aperture, along with shutter speed and ISO, forms the exposure triangle. Adjusting the aperture changes the amount of light reaching the sensor, which impacts the exposure directly. A larger aperture allows more light, making the image brighter, while a smaller aperture reduces light, darkening the image.
Aperture affects the image sharpness
Most lenses have an optimal aperture (often between f/8 and f/11) where they achieve maximum sharpness. Using apertures much wider or narrower can reduce image quality due to optical limitations like diffraction.
That´s why, for example, landscape photographers usually do not go for extremely small apertures – it will not create the sharpest image, but rather give the opposite effect.
Aperture and depth of field
Depth of field refers to the area of an image that appears sharp. With aperture, you can control how blurry is background. A wide aperture (low f-stop like f/2.8) creates a shallow depth of field, ideal for portraits where the subject stands out against a blurred background. On the other hand, a small aperture (high f-stop) gives a deep depth of field, with a detailed and sharp background, which is perfect for landscapes.
What aperture to use for shallow depth of field?
To achieve a shallow depth of field, use a wide aperture, which means a low f-stop number. Typically, apertures between f/1.4 and f/4 are ideal for creating a shallow depth of field.
What aperture gives the sharpest image?
Every lens has different widest and smallest aperture available. The sharpest images are usually obtained at the mid-range aperture, the so-called “sweet spot”. This is typically between f/8 and f/11. To find the “sweet spot” for your lens, try several apertures in the middle of its available range.
Aperture on different lenses
Different lenses offer varying aperture ranges. Yes, that means that not all lenses can create equally well nicely blurred backgrounds. Aperture is a physical characteristic of the camera lens therefore the range of f-stops available in camera settings will be different depending on the lens.
Prime lenses typically have wider maximum apertures compared to zoom lenses, which often have variable apertures. For example, a 50mm prime lens might have a maximum aperture of f/1.8, while a 70-200mm zoom lens might range from f/2.8 to f/4. That’s also a reason why prime lenses are more expensive.
You can check the maximum aperture of your lens on the top of it (e.g. 1:2.8 means the maximum aperture is f/2.8) or in the specifications.
Aperture and bokeh shape
Another thing that the aperture affects is the bokeh shape on the photo. The way how the blades of the aperture close is more or less the shape of the bokeh you get in the photo.
A lens with more circular-shaped blades produces round bokeh highlights, which are generally considered more pleasing.
What aperture to use and when
There is no one right answer to what aperture you should use since it all depends on the genre of photography and the desired effect. In the table below you will find recommended aperture ranges for various types of photography, which will help you to start. Start with the following f-stops and adjust as needed to achieve the effect you want.
Aperture for different types of photography| Photography genre | Recommended aperture | Effect |
|---|---|---|
| Portrait photography | f/1.4 to f/5.6 | Shallow depth of field to isolate the subject |
| Landscape photography | f/8 to f/16 | Deep depth of field for sharpness throughout the scene |
| Macro photography | f/2.8 to f/5.6 | Balance between shallow depth of field and sharpness |
| Street photography | f/5.6 to f/8 | Balance between background detail and subject isolation |
| Sports photography | f/2.8 to f/4 | Wide aperture for fast shutter speeds and subject isolation |
| Night photography | f/1.8 to f/5.6 | Capturing more light in low-light conditions, reducing noise |
| Family portrait photography | f/4 to f/8 | All family members are in focus while some background blur is maintained |
| Architectural photography | f/8 to f/11 | Sharpness and detail across the entire image |
| Product photography | f/8 to f/16 | Entire product is in sharp focus |
How to use aperture: setting it correctly
There are several ways to set the aperture on the camera:
- Manual mode: Switch your camera to manual mode (M), then adjust the aperture using the camera's dial or menu settings.
- Aperture priority mode: In aperture priority mode (marked as A or Av), you set the desired aperture, and the camera automatically adjusts the shutter speed for optimal exposure. It’s a perfect way for new photographers who are not experienced enough yet to use manual mode.
How to set the aperture on different cameras
- DSLR cameras: Use the lens aperture ring or camera dial. On some cameras, to set aperture you need to hold the AV button and turn the dial at the same time.
- Mirrorless cameras: Adjust through the camera menu or touch screen.
Conclusion: how the aperture works and when to use what aperture
Understanding the camera lens aperture is crucial for any photographer aiming to deliver high-quality photos. By experimenting with different aperture settings, you can control depth of field, exposure and image sharpness and shoot more creative and better-quality photos. There is no right aperture for all scenarios, but if you analyse the light conditions and the desired effect, you will find the sweet aperture for your scene.
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