Canon Rebel T8i Background Blur: Aperture, Distance, Lenses

To blur the background on a Canon EOS Rebel T8i, put the camera in aperture priority mode, set the lowest f-number your lens allows, zoom in, and stand close to your subject while keeping the background far behind them. Canon's 18-55mm STM kit zooms only give strong blur at 55mm and their closest focus distance, while a fast lens like the EF50mm f/1.8 STM makes soft, round background blur much easier.

Why a background blurs: four simple levers

A soft background is not a special effect hidden in a menu. It comes from four things you control: the size of the lens opening, how close you stand, how far you zoom in, and the size of the camera's sensor. Each one is a little lever. Pull two or three together and the background melts away.

Lever 1: aperture (the f-number)

The aperture works like the pupil of your eye. In the dark your pupil opens wide, and in bright sun it shrinks to a dot. A lens does the same thing, and the camera shows the size of that opening as an f-number.

Here is the part that trips everyone up at first, so do not worry if it feels backwards. A small number means a big opening. f/1.8 is a wide-open pupil, and f/8 is a tiny one.

A big opening gives you a thin slice of the picture that looks sharp. That slice is called depth of field. Picture a friend's face in focus while the trees behind them turn into soft blobs of green: that is shallow depth of field. The T8i has top and rear dials for direct control of both shutter speed and aperture.

Lever 2: distance

Two distances matter. The first is how close you are to your subject. The second is how far your subject is from the background.

Think of a person standing with their back against a brick wall. The wall is almost as close as they are, so it stays fairly sharp. Now ask them to take twenty steps away from the wall, toward you. Same lens, same settings, and the wall goes soft. Moving your subject costs nothing, and it often helps more than any setting.

Lever 3: focal length (how zoomed in you are)

Focal length is the number in millimeters on your lens. A small number like 18mm shows a wide view, like standing back to fit a whole room in. A bigger number like 55mm brings things closer, like looking through a short telescope.

In its review of the EF-S 18-55mm f/3.5-5.6 IS STM, The Digital Picture explains that a fairly wide focal length range plus a fairly narrow aperture gives deep depth of field, so strong background blur is not that lens's strength. In plain words: zoomed out wide and with a small opening, most of the scene stays sharp. Zoom in to get more blur.

Lever 4: the sensor

The Rebel T8i uses an APS-C sensor with a 1.6x crop factor. The sensor measures 22.3 x 14.9 mm. Any lens you mount frames the scene like a lens 1.6x longer would on a full-frame camera. So a 50mm lens on your T8i shows about what an 80mm lens shows on full frame.

For you, this mostly changes where you stand. With a 50mm lens, you step back a little to fit someone's head and shoulders in the frame.

Set up your T8i for background blur

Use aperture priority mode

In aperture priority mode, you choose the f-number and the camera chooses the shutter speed for you. It is like driving with cruise control: you steer, and the camera handles the speed. Digital Trends describes the T8i's mode dial as large and simple.

If you are new to this, the T8i comes with a Guided menu that explains how aperture priority can be used to blur a background behind your subject. Canon's traditional menu is still there when you want more precise control. Once you are in aperture priority, use the dials to set the lowest f-number your lens will go to.

Choose where the camera focuses

Blur only looks good when the right thing is sharp. Through the viewfinder, the T8i offers Single-point AF, Zone AF, Large Zone AF and Auto AF point selection. In Auto AF point selection, all 45 points are active and the closest subject gets priority. That means a flower or a fence post in front of your friend could steal the focus.

For portraits, Single-point AF is the safer start, because you pick the one point that lands on your subject.

If you shoot using the rear screen instead, the T8i switches to a 143-point array that covers more of the frame and adds eye AF. TechRadar calls the camera's Dual Pixel phase detection AF rapid and reliable. TechRadar also noted that the camera's performance dips in live view mode, so if things feel slow on the screen, the viewfinder is a fine fallback.

Try back-button focus later

The T8i has a dedicated AF ON button on the back. With back-button focus, that button handles focus and the shutter button only measures light and takes the picture. It is handy for focusing once on a face and then reframing. You do not need it to get a blurry background, so save it for when the basics feel easy.

What each lens can do for blur

The lens you own matters as much as the settings. This table compares four Canon lenses named in T8i and lens reviews. The widest aperture comes from the lens name, and the full-frame framing uses the T8i's 1.6x crop factor.

Lens	Widest aperture	Frames like (full frame)	What reviews say
EF-S 18-55mm f/4-5.6 IS STM (T8i kit lens)	f/4 at 18mm, f/5.6 at 55mm	28-88mm	TechRadar calls it slightly soft
EF-S 18-55mm f/3.5-5.6 IS STM (older kit lens)	f/3.5 at 18mm, f/5.6 at 55mm	about 29-88mm	Strong blur only at 55mm and closest focus; 7-blade circular aperture
EF-S 18-135mm f/3.5-5.6 IS STM	f/3.5 at 18mm, f/5.6 at 135mm	about 29-216mm	Named as a good standard zoom option for the T8i
EF50mm f/1.8 STM	f/1.8	80mm	7-bladed aperture for circular background blur; focuses as close as 35 cm

Getting the most from the kit lens

The T8i is sold body-only or with the EF-S 18-55mm f/4-5.6 IS STM. Digital Camera World says its focal range covers everything from wide landscapes to portraits. For blur, you have to work it a bit.

Zoom all the way to 55mm, set the lowest f-number the lens allows there, and get as close as the lens will focus. The Digital Picture found that its close cousin, the EF-S 18-55mm f/3.5-5.6 IS STM, does not create a strongly blurred background unless you shoot at minimum focus distance at 55mm. Because these are variable aperture zooms, the widest setting changes as you zoom toward the long end. Seeing the number jump from f/4 to f/5.6 as you zoom is normal, not a mistake.

Small subjects work best with the kit lens. A flower, a coffee cup or a toy, shot close at 55mm with the background far away, can look lovely. A full-body portrait from across a room will mostly stay sharp.

The EF50mm f/1.8 STM: the easy upgrade

A prime lens does not zoom, and that lets it have a much bigger opening. The EF50mm f/1.8 STM opens to f/1.8. Compared with f/5.6 on the kit lens at 55mm, that is a much wider pupil, so the slice of sharpness gets much thinner.

Canon says this lens uses a 7-bladed aperture, up from 5 blades on the older model, for circular background blur that makes your subject stand out. The look of that blur is called bokeh. Round blades turn background lights into soft circles instead of sharp-edged shapes.

It also focuses as close as 35 cm, with a maximum magnification of 0.21x. Its stepping motor gives quieter autofocus than the older version, and you can fine-tune focus by hand even in AF mode. It fits the T8i because the camera accepts EF lenses as well as EF-S lenses. TechRadar also suggests EF lenses can help unlock the T8i's talents in a way the kit lens cannot.

Step by step: a blurry-background portrait on the T8i

1. Find a background that is far away: an open field, a long hallway, trees across a park.
2. Place your subject well in front of it, many steps from any wall or fence.
3. Turn the mode dial to aperture priority.
4. Set the lowest f-number your lens allows. On the kit lens, zoom to 55mm first.
5. Choose Single-point AF and put that point on the nearest eye.
6. Move closer until your subject fills a good part of the frame.
7. Press halfway, or press AF ON if you set up back-button focus, then take the shot.
8. Zoom in on the photo on the rear screen and check that the eye is sharp.

When the background still looks busy

Every photographer takes plenty of shots where the background stays sharp. Each one tells you which lever to pull next.

• The background is sharp and your subject is soft. The camera probably focused on the wrong thing. Switch away from Auto AF point selection, which favors the closest subject, and pick one point yourself.
• Everything looks sharp. Check your zoom and f-number. Zoomed out wide with a narrow aperture gives deep depth of field.
• The blur is weak. Move closer to your subject, and move your subject farther from the background.
• The background is messy even when blurry. Change your angle. The T8i has a vari-angle touchscreen, which makes it easier to shoot from low down against the sky or from up high against grass.
• Something odd shows up at the edge. The viewfinder shows only 95% of the frame, so a little more lands in the photo than you saw. Leave a bit of space at the edges.

If you are still choosing a camera

The Digital Picture notes that the Rebel T8i has been replaced by the Canon EOS R50. Everything above about aperture, distance and focal length works the same on any camera. The Canon R50 background blur guide covers the newer camera, and the Canon Rebel T7 background blur guide covers the T8i's entry-level sibling.

Start with the lens you have. Pull one lever at a time, look at the result, and adjust. Soon you will know before you press the shutter how soft that background is going to be.