Adding background blur in post gives your footage a shallow depth-of-field look even when your lens didn’t deliver one on set. DaVinci Resolve has three native ways to do this, each suited to a different skill level and workflow speed. This guide walks through all three methods so you can pick the right one for your shot and get a result that looks intentional rather than processed.
Why Your Footage Needs Background Defocus in Post
Not every shot gets the luxury of a wide-aperture lens or a controlled lighting setup. When your background competes too strongly with your subject, adding defocus in post separates the two planes visually and guides the viewer’s attention where it belongs. The goal is to simulate the natural optical blur a fast lens would have produced, creating a smooth, gradual falloff behind the subject.
Method 1: Defocus Background Using the Fusion Page (Recommended)
The Fusion page gives you the most precise, professional control over background defocus. You work with a node tree that isolates the subject, applies optical blur only to the background layer, and composites the two back together. This method handles complex edges and moving subjects better than any other approach inside DaVinci Resolve.
Step 1 — Open Your Clip in Fusion
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Place your clip on the timeline in the Edit or Cut page.
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Select the clip so it is highlighted in the timeline.
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Click the Fusion tab at the bottom of the interface, or press Shift + 6.
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The Fusion page opens with a default node tree: MediaIn1 connected to MediaOut1. This is your starting point.
Step 2 — Create a Mask to Isolate the Subject
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Add a B-Spline or Polygon mask without selecting any node first. Go to Tools > Mask > B-Spline / Polygon, or right-click in the node area and browse the same mask tools. The mask drops into the workspace unattached.
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Click the B-Spline node to select it, then trace around your subject in the viewer by clicking to place control points.
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In the Inspector, set Soft Edge to a value between 0.02 and 0.06 to feather the mask edge. The exact value depends on your resolution.
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Check the Invert checkbox in the Inspector so the mask covers the background instead of the subject.
Note: If your subject moves during the clip, you will need to keyframe the mask shape at regular intervals or use the built-in Fusion tracker to animate the mask automatically. Scrub through the clip before moving to the next step to identify any frames where the mask drifts.
Step 3 — Add the Defocus Node and Wire Everything Together
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Add a Defocus node from Tools > Blur > Defocus.
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Connect MediaIn1's output to the Defocus main input (the larger triangle on the left of the node).
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Connect the B-Spline output to the Defocus effect mask input (the blue triangle on the side of the node).
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In the Inspector, adjust the Size parameter. Values between 0.01 and 0.04 produce a realistic shallow-depth-of-field look. Beyond 0.06 starts to look artificial.
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Connect the Defocus output to MediaOut1.
Method 2: Defocus Background on the Color Page (Faster Workflow)
The Color page method skips Fusion entirely and works well for static shots or any clip where you need results quickly without building a node tree.
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Open your clip in the Color page by clicking the Color tab at the bottom of the interface.
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In the toolbar above the viewer, click the Power Window button (the shape icon that looks like a pentagon). Select a shape that fits your subject, typically an ellipse or polygon.
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Draw the Power Window around your subject in the viewer. Size and position it to cover the subject as closely as possible.
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Click the Invert button inside the Power Window controls so the selection now targets the background instead of the subject.
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Increase the Softness sliders on the Power Window to feather the edges and avoid a hard cutout look.
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Open the Blur palette (the third icon in the bottom-left panel cluster) and raise the Radius value, or navigate to the OpenFX panel, find a blur plugin such as Soften, and apply it to the node. Adjust the blur strength until the background separation reads clearly without looking heavily processed.
Note: The Color page method is faster to set up but offers less mask precision than Fusion. It works best on static shots with a clearly defined subject. For footage with significant subject movement, the Fusion method will produce cleaner results.
Method 3: Quick Blur Mask on the Edit Page (Beginner Option)
This is the lowest-friction starting point if you have not yet explored Fusion or the Color page. Expect less edge quality, but it is fast and requires no node knowledge.
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With your clip on the timeline in the Edit page, open the Effects Library panel on the left and search for Gaussian Blur. Drag it onto your clip.
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Open the Inspector panel on the right and click the Video tab. You will see the Gaussian Blur effect listed with a Strength or H/V Blur slider.
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Increase the blur strength until the background reads as defocused. At this stage, the blur applies to the entire clip.
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Below the effect settings in the Inspector, look for the Mask tool options. Click Add Mask and choose a shape. Draw it around your subject.
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Check the Invert Mask option so the blur is restricted to everything outside the subject boundary. Adjust the mask Feather slider to soften the edge.
The Edit page method has the least control over edge quality and no optical lens simulation. It is best suited for static shots where the subject is clearly separated from the background and cinematic realism is not the primary goal.
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Tips for Making Background Defocus Look Natural
Applying blur is easy. Making it look like it came from a real lens takes a bit more attention. Keep these points in mind before you export:
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Match blur intensity to lens reality. A 50mm lens at f/1.8 produces a specific, moderate background blur. Cranking your defocus value to the maximum almost always looks artificial. Start subtle and increase only as needed.
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Always feather your mask edges. A hard-edged mask is the fastest way to expose the composite. The transition between sharp and blurred areas in real photography is always gradual.
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Blur should increase with distance. Objects further from the subject should appear more blurred than objects just behind them. If your background has depth, consider multiple blur layers or a gradient mask.
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Hair and fine edges are the hardest areas to sell. Avoid over-blurring areas directly adjacent to hair or transparent elements. Slightly under-blurring around these edges often reads more convincingly than a perfect mask.
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Keyframe masks for moving subjects. A mask that does not follow the subject will reveal the background layer at clip edges. Even semi-automated tracking with Fusion’s tracker saves significant time over frame-by-frame manual adjustment.
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Review on a properly calibrated monitor. Defocus effects that look balanced in a dim room can look obviously processed on a color-accurate display. Check before you commit to an export.
FAQ
Q1: What is the difference between the Blur node and the Defocus node in DaVinci Resolve Fusion?
The Blur node applies uniform pixel averaging across the selected area, producing a flat, uniform softness. The Defocus node simulates the optical behavior of a real camera lens, including realistic bokeh falloff and specular highlight rendering. For any project where the background blur needs to look like it came from a camera, use Defocus rather than Blur.
Q2: Can I defocus a moving subject’s background in DaVinci Resolve?
Yes, but the mask must follow the subject throughout the clip. In Fusion, you can keyframe the mask shape manually at key frames, or attach a tracker to the mask node so DaVinci Resolve semi-automates the movement. For fast or complex motion, plan to spend time on rotoscoping to maintain clean edges across every frame.
Q3: Does DaVinci Resolve Free support background defocus in Fusion?
Yes. The Fusion compositor is fully included in the free version of DaVinci Resolve. The Defocus node, B-Spline masks, Merge nodes, and all the tools described in Method 1 are available without purchasing DaVinci Resolve Studio. The free version handles this workflow completely.
Q4: Why does my background blur look choppy or unnatural on edges?
The most common cause is insufficient feathering on the mask. A hard mask edge creates a visible seam where the sharp subject meets the blurred background. Increase the Softness or Feather value on your mask until the transition is gradual. Even a small increase in softness can dramatically improve how convincing the composite reads.
Conclusion
For the cleanest, most realistic result, use the Fusion page with a B-Spline mask and the Defocus node. When you need speed and your shot is relatively static, the Color page Power Window method gets you there faster. The Edit page option works as a quick experiment or a placeholder before you refine the shot later. Once you are comfortable with basic background defocus, explore DaVinci Resolve’s built-in mask tracker, rotoscoping tools, and depth map techniques to handle more demanding shots with greater efficiency.
