Defocus

Resolve 21 places Defocus in the Fusion Blur Nodes chapter. It has two physical inputs: the orange Input for the primary 2D image and an optional blue Effect Mask. The mask limits where the already-processed effect contributes; it is not a depth map, aperture map or second image source.

Filter selects Gaussian Blur or Lens. Blackmagic describes Gaussian as the simpler, faster method and Lens as the more realistic but significantly slower method. Lens is therefore most useful when out-of-focus highlight shape is actually visible rather than as a generic replacement for every ordinary blur.

Lock X/Y applies the same defocus amount to both axes. Disabling it exposes independent horizontal and vertical control. That can be used deliberately for anisotropic styling, but Defocus does not automatically model a real anamorphic lens merely because X and Y differ.

Defocus Size sets the core amount of defocus. Higher values blur more strongly and also produce larger blooms. A clean workflow is to set Bloom Level to 0 first, tune the core defocus, then add bloom as a separate decision.

Bloom Level and Bloom Threshold do not replace the main defocus. The manual states that pixels above Bloom Threshold are defocused and receive an added glow/bloom, while pixels below the threshold are still defocused but do not receive that added bloom. Bloom Level controls the intensity and size of blooming on the eligible bright pixels.

Four Lens controls are available only when Filter is Lens. Lens Type chooses the basic bokeh/aperture shape. The current captured Inspector shows four choices; Blackmagic's Fusion tool reference identifies them as NGon Solid, NGon Shaded Out, NGon Shaded In and Circle. Angle, Sides and Shape refine the NGon behavior.

Lens Angle rotates the aperture shape, Lens Sides sets the number of NGon sides, and Lens Shape controls how pointed the NGon becomes: higher values are more pointed/star-like while lower values are smoother. Resolve 21 explicitly states that Angle, Sides and Shape have no visible effect when Lens Type is Circle.

Clipping Mode is a Domain-of-Definition boundary control, not a creative blur-strength preset. Frame uses the full frame and treats regions outside a smaller upstream DoD as black/transparent. Domain respects the upstream DoD and can produce stronger clipping with a large filter. None performs no source-image clipping; required samples outside the upstream DoD are treated as black/transparent.

Defocus should not be confused with Depth Blur. A single Defocus applies one 2D filter model to the image region admitted by the node and its Effect Mask; it does not inspect Z or automatically keep one distance sharp while another goes out of focus.

In production, choose Gaussian when the task is simply softening and Lens when aperture character matters. Judge Lens on real point highlights, and judge Clipping Mode on sources with limited DoD or transparent edges against the actual downstream composite background.

Defocus has no native concept of focus distance. Animating Defocus Size can stylize a focus pull, but mathematically it changes one global 2D blur amount rather than moving a physical focus plane through Z.

Gaussian and Lens should be compared on the same source with the same Size and Bloom state. Changing Size, Filter and Bloom together destroys causal diagnosis.

Gaussian is not merely a temporary preview mode. For technical softening without visible bokeh geometry it can be the more predictable final production choice.

Lens earns its extra cost when out-of-focus highlights are large enough for aperture geometry to read. On uniform texture the slower model may bring little visible benefit.

Lock X/Y is a constraint between the horizontal and vertical blur amounts. Disabling it creates anisotropic defocus, but anisotropy alone is not automatically a physically correct anamorphic-lens simulation.

With Lock X/Y off, circular and diagonal highlights reveal accidental X/Y imbalance quickly, so asymmetric settings should be judged on clear geometric cues.

Bloom is an additional highlight response on top of the base defocus. Threshold is not a mask for the entire blur and does not decide which pixels stay sharp.

Bloom Threshold must be judged in the actual working range. A value that behaves well in display-referred material can behave very differently in linear/HDR or extended float signals.

Bloom Level controls the blooming of selected highlights; excessive Level can hide the underlying Lens shape and create the impression that Defocus Size itself increased.

With Lens Type = Circle, Angle, Sides and Shape become visually irrelevant because the aperture is round. This is a conditional behavior boundary rather than a node failure.

NGon Solid, NGon Shaded Out and NGon Shaded In differ at the aperture-model level, while Angle, Sides and Shape further modify the chosen NGon geometry.

Lens Sides is easiest to evaluate on isolated point highlights. On diffuse detail, polygon geometry can disappear into what looks like an ordinary blur.

Lens Shape is not a generic sharpness control. It changes the NGon from smoother toward more pointed/star-like forms and should be tuned after Lens Type and Sides.

Clipping Mode is a boundary/Domain-of-Definition control. The wrong mode can look like clipped bloom or blur at the edge even when Size and Lens settings are correct.

On full-frame MediaIn sources, None/Domain/Frame may look similar. Test them on limited DoD, transparent padding, small graphics, or large blur footprints.

Large defocus requires samples around source pixels. When upstream data are absent outside the DoD, the filter boundary becomes part of the visual result and black/transparent assumptions matter.

Effect Mask limits node contribution but does not turn Defocus into depth-aware DOF. A grayscale gradient mask can vary the mix spatially, but it still gates one calculated effect rather than reading Z.

If blur radius itself must vary from a map, Vari Blur or Depth Blur solve a different problem; the Defocus Effect Mask is not a blur-radius map.

With a masked local defocus, mask feather and large Size can interact perceptually. Judge mask falloff separately from bokeh shape.

Placement relative to Merge is fundamental: Defocus before Merge processes one branch, while Defocus after Merge processes the assembled composite.

On text, UI and thin graphics, Lens mode can destroy readability sooner than a numeric Size suggests. QC must include delivery scale rather than only a zoomed Viewer.

On premultiplied graphics, strong blur can expose contaminated RGB behind alpha. Do not treat Bloom or Clipping Mode as random cures before checking premultiplication.

Defocus is not a replacement for camera depth of field inside Renderer3D. Decide whether DOF belongs in the 3D render or after flattening to 2D.

For animation, Size/Bloom/Lens controls need target-build and curve-level playback checks. Static documentation defines control meaning, not ideal temporal interpolation.

Lens can be expensive at high resolutions and large Size values. Profile playback/render cost before duplicating several Lens Defocus nodes across branches.

For technical A/B work, keep Common Settings Blend and Process channels at a baseline so host-level mixing does not obscure core Defocus math.

A production preset should record Filter, Bloom state, Lens Type and Clipping Mode as well as Size; the same Size number in a different context is not the same look.

When UI labels or serialized IDs change across Resolve/Fusion versions, a live .setting/.comp export from the target build takes precedence over an old screenshot or historical manual.