Knowing what aperture to use to create a beautiful background blur is one of the easiest ways to improve our portraits. It’s a great effect because it creates a clutter free background, which is essential in making sure our subjects pop!
You need to be shooting in manual mode to get those blurry backgrounds on purpose! So if you’re not, familiarise yourself with the exposure triangle and jump in!
Related: Getting out of Auto
But if you are shooting in manual mode, then you’ll know you need a wide open aperture to get those blurry backgrounds. And this is where people run into difficulty, when it comes to selecting the right camera settings and choosing the best lens for group photos.
“When would you use a 1.4 aperture?”, “How do I know what aperture to use?”, or “When would you use low aperture?” are some of the questions I receive most often.
To help you get all the answers, in today’s post we’ll have a closer look at what aperture is, so that you can confidently decide which one to use next time you’re photographing a large group of people or shooting landscape photography.
Aperture is one of the three elements that controls exposure in your camera, while also affecting your depth of field. It refers to the physical opening of your lens, and is measured in f stop (eg. f/1.8, f/3.5, f/11, f/2.8 etc).
Related: What is The Exposure Triangle
Depth of field is the area of focus in front of and behind the point where you focused (that would be your subject!).
How much depth of field you have is controlled by your aperture setting. Remember aperture range is measured in f stops:
We use wider aperture for blurry backgrounds, such as an image of a flower or person and then everything behind it is out of focus.
Unlike a large aperture, a narrow aperture of the lens is used when we take a photo where we want to get everything from front to back to be in sharp focus, such as a landscape image.
The size of aperture can range from small aperture to maximum aperture with many variations in between as we open up and shut down our lenses… see our very technical diagram!
You can see in our beads example below… at f/2 (known as a wide aperture) we have only one bead in focus.
When we increase the f stop to f/8 (also known as stopping down or closing down the aperture) we have more beads in focus behind the bead that we focused on.
Now let’s imagine our beds are the heads of an extended family grouped together! We want to ensure all our people in a group will be clear and in focus.
I get asked this question often by people trying to get their camera settings right and choosing the best lens for group photos, and the answer is not what you’d expect!
When you focus on a subject everything to their side is on the same focal plane, and will also be in focus. So this means if you’re taking a large group photo and every person is standing side by side in a straight line, and you were standing directly in front of them, they would all be in focus at a wide aperture. Whether the group was 2 people or 50 people!
Because the issue here is depth not width, or focal plane in photography speak.
In this graphic everyone would be in focus regardless of aperture range because they’re all standing next to each other… ie. on the same focal plane!
And here’s a real life example… a family of four all sitting pretty much at the same focal plane, shot at f/2.8 and all in sharp focus. This is the perfect hyperfocal distance.
Outside of that focal plane, you will see a gradual reduction in focus, in front and behind the subjects. So when taking photos of groups with people several deep, other than using the best lens for group photos, you also need a deeper depth of field to ensure everyone is in focus from front to back.
And we adjust that depth of field by closing down the aperture (increasing f stop number). This family was photographed with an aperture of f/5.6 because they’re sitting on roughly 3 separate focal planes. The deeper your group of people, the more depth of field you need to get them all in focus.
Conversely, this extended family with far more people than the image above, was shot at f/4.5 but everyone is in focus because they’re sitting on just 2 focal planes.
In manual shooting, aperture controls depth of field. But it’s also affected by the length between the camera lens and subject, and even your camera model. So to give you an exact f stop that works for every situation would require knowing all those variables each time.
There are depth of field calculators online, however it’s not exactly practical to pause between every shot to calculate!
I personally think it’s easier to simply pick a generous but not over the top aperture, take a shot, zoom in a little on your LCD screen and scroll around to check everyone is in focus.
Try these settings as a starting point, and from there you can adjust:
2 people deep / 2 focal planes) – f/4
3 people deep / 3 focal planes) – f/5.6
4 people deep / 4 focal planes – f/7.1
…and so on.
If everyone in the group is not in focus, adjust your aperture to a higher f-stop, and check again.
Don’t be looking for tack sharp faces because once your zoom range is all the way in. you’re in pixel peeping territory, and a loss of sharpness is normal.
Out of focus is different, it looks a little like motion blur.
Once you start getting into bigger groups of people, say 15-20, you want to try to keep them to 3-4 focal planes so that you don’t have to shoot at apertures that will put the entire scene into focus and thereby lose any bokeh whatsoever!
As depth of field recedes in front and behind the point of focus, the best technique is to focus on someone in the middle focal plane.
Now we know that the narrower the aperture, the more our background comes into focus. So how do we get everyone in focus, and still ensure beautiful blurry backgrounds?
Remember we said depth of field is not only affected by aperture, but also by distance between subject and background, and your lens focal length?
So an easy way to get a blurry background is by using a lot of distance between your subjects and the background. In this image below the subjects were about 3-4 metres from the garden behind them.
The second thing you can do is use longer or prime lenses, because unlike zoom lenses, long focal lengths compress the background. The best lens for group photos in my opinion is a 135 mm. This gives you the ability to capture a larger group without the use of rows.
The image above was taken with my 135mm lens which gave me a beautiful background bokeh.
Related: Lou’s Favourite Lens