Resolve FX · Blur · 05
Lens Blur simulates an aperture-driven optical blur rather than a neutral mathematical softening. It is useful when the blur itself should carry lens character: shaped bokeh, anamorphic stretching, highlight response and aperture geometry.
This guide follows the real DaVinci Resolve 21 panel: Shape Type, Aperture Shape, Quality, Blur Alpha, Blur Size, Blade Curvature, Rotation, Anamorphism, Chroma Shift, Highlights, Apodization, Catadioptric and Global Blend.
Controls
Blur Size controls the amount, but the identity of the effect comes from aperture geometry and optical modifiers. That is why Lens Blur is often chosen when Gaussian Blur looks too neutral.
Lens Blur differs from a regular Gaussian Blur because the blur character follows an aperture model. Shape Type changes how the aperture is built, while Aperture Shape defines its geometry from Triangle and Square through Hexagon, Heptagon and Octagon.
Quality controls the processing trade-off: Full uses the highest setting, Half works faster and Quarter is faster still. Blur Alpha includes the alpha channel in the blur and matters for keyed or transparent elements.
Blur Size controls the blur scale. Blade Curvature and Rotation change the aperture character, Anamorphism stretches the shape, Chroma Shift introduces colour separation, Highlights affects bright areas, while Apodization and Catadioptric alter the bokeh character.
Global Blend mixes the configured Lens Blur back with the original image. A useful approach is to build the desired bokeh and blur first, then reduce the entire effect with Blend without changing the rest of the controls.
Aperture geometry
Triangle, Square, Pentagon, Hexagon, Heptagon and Octagon produce different highlight and bokeh geometry. Preview Shape is useful when you want to understand the aperture before judging the final frame.
Practical use
Use aperture shapes and Blur Size when you want the background blur to feel more photographic than Gaussian softening.
Anamorphism stretches the bokeh and can help mimic a wider optical character without turning the whole effect into a generic directional streak.
Highlights, Apodization and Catadioptric controls are useful when bright points need a more deliberate bokeh response.
Place Lens Blur on a dedicated node and limit it with a window or key when only the background or a selected region should receive the effect.
Typical mistakes
Aperture character becomes obvious quickly. If the whole frame turns into huge polygonal bokeh, the effect starts looking synthetic.
Chroma Shift, strong Anamorphism and aggressive bokeh controls can fight each other. Build one optical idea at a time.
Full is useful for final judgement, but Half or Quarter can be more practical while tuning a heavy shot.
Lens Blur is often more convincing on a controlled region than across the entire image. Use node isolation when the foreground must stay sharp.
Lens Blur vs Gaussian Blur
Choose it when aperture geometry, bokeh and optical character are part of the image design.
Choose it when you simply need a clean neutral soft blur without aperture-shaped bokeh.
Lens Blur is not simply a stronger Gaussian. Use it when the defocus pattern itself matters: aperture shape, bokeh highlights, anamorphism and the optical character of out-of-focus light.
| Control / layer | Meaning | Inspection point |
|---|---|---|
| Aperture / blades | Shape of the footprint and bokeh discs. | Use bright point highlights as a diagnostic test. |
| Bokeh / highlight controls | Determine how strongly bright regions dominate the defocus. | Watch clipping and unnatural halos on faces/skin. |
| Anamorphism | Stretches the bokeh character along one axis. | Match the rest of the shot’s lens language; arbitrary stretching looks synthetic. |
| Quality / Blend | Trade-off between bokeh detail, speed and final effect amount. | Judge final quality on highlights and thin edges. |
Likely cause: The problem is matte/overlap, not aperture shape.
Fix: Fix the matte/edge softness before changing bokeh controls.
Likely cause: Uniform blur across depths and oversized highlights.
Fix: Separate depth planes or use CineFocus/depth mattes.
Likely cause: Grain was blurred with the image.
Fix: Place grain after Lens Blur or restore texture separately.
High-quality optical bokeh costs more than a simple Gaussian. On heavy 4K/8K shots, use node cache and reserve enhanced quality checks for the final stage.
Aperture/blur amount can be animated as a rack-defocus, but without depth logic the change remains global. A real focus pull between planes needs controlled mattes/depth or CineFocus Focus Distance.
Lens Blur is usually placed after the base grade and before final grain. If a dedicated correction is creating highlights for bokeh, that correction belongs before Lens Blur in that branch.
rectangular local averaging shaped by Iterations
simple controllable blur with H/V and channel shaping
smoothly weighted blur without a directional vector
natural softness, defocus beds and clean-up
linear vector driven by Angle
motion smears and horizontal/diagonal streaks
discrete cells and pixelation
detail concealment and graphic stylisation
rotation around a centre
spin, vortex and rotational motion
rays toward or away from a centre
rush, punch-in/out and depth-like transitions
depth-aware virtual lens
different defocus across foreground, subject and background
Where to place FX and preserve operation order.
How to localise blur and keep the matte tracked over time.
Coordinates, crop/zoom and FX-centre behaviour after transforms.
Check RGB contamination, clipping and technical side effects.
Control names and panel layout are also cross-checked against the real DaVinci Resolve 21 screenshots shown earlier on this page. Where Blackmagic does not publish implementation math, this guide describes observable behaviour and does not invent a proprietary kernel.
FAQ
Lens Blur simulates an aperture-shaped optical blur. It gives you control over aperture geometry, blur size, anamorphism, chroma shift, highlight behaviour and final blend.
Gaussian Blur is a neutral smooth blur. Lens Blur adds aperture geometry and optical character, making the bokeh itself part of the visual result.
It changes the geometry of the blur and bright bokeh spots. Triangle, Square, Pentagon, Hexagon, Heptagon and Octagon each create a different shape.
Full is the natural choice for final evaluation. Half and Quarter can make interactive tuning faster when performance matters.
It mixes the entire configured Lens Blur with the original image, letting you reduce the effect without rebuilding the optical settings.
Blur catalog
Different goal
Choose Mosaic Blur when the goal is deliberate pixelation or concealment rather than optical defocus.
