Depth of Field and Bokeh: How to Blur the Background

A sharp subject against a soft, creamy background is one of the most loved looks in photography. It's controlled by depth of field: how much of the scene, front to back, appears sharp.

The four factors behind depth of field

1. Aperture: wider apertures (f/1.4, f/1.8) give shallower depth of field.
2. Focal length: longer lenses appear to blur backgrounds more at the same framing.
3. Distance to subject: the closer you are to the subject, the shallower the depth of field.
4. Distance from subject to background: the further the background, the blurrier it looks.

Sensor size also plays a role at equal framing; full frame gives slightly shallower depth of field than APS-C.

How to blur the background: a recipe

• Use your widest aperture (f/1.8–f/2.8)
• Use a longer focal length (85mm or more)
• Move closer to your subject
• Move your subject away from the background
• Choose a background with lights or texture for beautiful bokeh

What is bokeh?

Bokeh is the quality of the out-of-focus areas: smooth or busy, round or shaped highlights. It depends on the lens design and aperture blades. Points of light in the background, like fairy lights or street lamps, become glowing circles.

Focus at wide apertures

At f/1.4, depth of field can be a few millimetres. Tips:

• Use eye-AF and focus on the nearer eye
• Avoid focusing then recomposing at close distances
• Stop down to f/2.8 for more forgiveness
• For two people, keep them on the same plane

When you want everything sharp

Landscapes, architecture, groups and product shots often need deep depth of field. Use f/8–f/11, a wider lens and focus about a third into the scene. For extreme close-ups, use focus stacking.

Phone portrait mode vs real bokeh

Phones simulate blur with software, which can smear hair and edges. Real depth of field from a large sensor and fast lens looks more natural.

Practice

Photograph a friend at f/1.8, f/4 and f/11 with the same framing, then try moving them closer to and further from the background.

Learn it hands-on

Depth of field is one of the first creative controls taught in RAP Education's courses, and the fashion and portrait masterclass uses it extensively in studio and location shoots.