The smaller the f-stop, the larger the aperture.

They run from f/1.4 (largest opening and most light let through) to f/32 (smallest opening and least light coming through). Most cameras start at f/2.8 or f/4. 

The maximum aperture on your camera is usually written on the edge of the lens. Often, it is displayed without the f-number. For instance, when the maximum aperture is 2.8, it may appear as ‘1:2.8’. This signals that the lens can maintain the maximum aperture of f/2.8 throughout the full zoom range.

F-stops don’t run in fixed numbers – instead, they follow this pattern:

F-stops with the largest opening

f/1.4 – lets in most light but only included on professional or semi-professional cameras

f/2.0 – again, most mainstream cameras don’t start at this level

f/2.8 – often the lowest f-stop on most cameras and useful for low light conditions

f/4.0 – a good choice for travel and nature photography

f/5.6 – the middle ground, good for photos of cities, buildings and landscapes – where there’s no single point of focus

f/8.0 – at this level you start to notice changes in depth of field with added background blur

f/11.0 – the size aperture starts to provide a nice depth of field, and can be used for macro photography

f/16.0 – the smallest aperture on many cameras 

f/22.0 – only go this small if you are more experienced, as sharpness levels can start to suffer

F-stops with the smallest opening.

As you go down the chart, each f-stop lets in half as much light. For example, the f/8.0 setting allows in half the light of f/5.6. These numbers are essentially fractions. So, an f/8.0 is an eighth, while f/2.0 is half. Thinking in these terms can help get your head around why the larger numbers mean smaller apertures – eighths are smaller than half. 

Both the foreground leaves and background mountains are in focus due to the low f-stop.

The model’s face is sharp but background blurred as a large f-stop has provided depth of field:

Usually, you’d choose a small f-stop in low light conditions to pick out detail. If you’re outside on a bright day, a larger f-number could prevent images from becoming washed out. 

Aperture and depth of field.

While the level of light let in is a key aspect of aperture, how aperture affects depth of field is also important. Depth of field is the range between the nearest and furthest objects in focus within a picture. 

Shallow depth of field – Use a wide aperture (or low f-number) to blur the background and help the photo’s in-focus subject pop. This effect, commonly known as the bokeh effect, is great for portraits or food photography.

Larger depth of field – Use a smaller aperture (or large f-number) to keep a greater amount of the frame in focus. This is perfect for group shots or scenic landscapes.

Here is the same photo with different aperture settings to adjust the depth of field:

Remember that opening the aperture lets in more light, so you might need to reduce the shutter speed if you want a shallow depth of field in bright conditions. Likewise, if you want to take a low light landscape shot, you’ll need a relatively open aperture with slow shutter speed and a tripod to reduce blur. 

Aperture and exposure.

The three main settings (ISO, aperture and shutter speed) all impact how much light is let into your camera. Another way of talking about this is the exposure – or, as it’s sometimes called, the ‘exposure triangle’.

The brightness of an image shows how exposed it was to light. Too much light can lead to an overexposed image. This could be because the:

• Aperture was too wide

• Shutter speed too long

• ISO setting too high

An overexposed image:

Images that are too dark are underexposed, due to the:

• Aperture being too small

• Shutter speed too short

• ISO setting too low

An underexposed image

Of course, images can be intentionally overexposed or underexposed to achieve a surreal effect.

Setting apertures on your camera

You can set the aperture on most cameras easily.

1. Select the Aperture Priority mode – usually signified with an A or Av. This allows you to choose the aperture size, but the shutter speed and ISO will be automatically selected. 

2. Next use an A or Av button – sometimes with an x/- next to it, to show that you are ready to adjust the aperture settings.

3. Use the control or command dial – scroll through the f-numbers.

4. Adjust to your preferred setting – this should show up on the screen as an f-number.

5. Check photo – adjust to make sure you’re getting the best image.

You can set Aperture Priority mode by switching to Av or A:

For more control, choose Manual mode – usually an M. This allows you to choose aperture size, ISO and shutter speed. Follow the steps above but simply select M instead of A or Av.

Which aperture setting is best?

The ideal aperture setting depends on the type of image you want and the shooting conditions. We’ve listed a few common subjects and suggested an aperture range for them. But remember that light conditions, movement of the subject and other settings also impact the end result.