PrismBlur

PrismBlur is a ResolveFX/OpenFX node available inside Fusion rather than a classic Fusion Blur tool. Blackmagic's training material describes the look as defective-lens behavior where different colors focus differently.

Position X/Y defines the center around which chromatic aberration is created. It is an optical center, not a Transform of the source image. The captured Resolve Inspector shows a centered 0.5 / 0.5 baseline.

Blur Strength softens the primary image. Treat it independently from the aberration pair so you can tell whether lost detail comes from blur or from the chromatic treatment.

Aberration Distance controls how far the aberration appears from the source image. Aberration Strength intensifies the zoom-blur mechanism used to create the chromatic aberration, so Distance and Strength should be tested as separate controls.

Vignette Size is specifically the built-in edge-vignette control: Blackmagic documents 0 as removing the vignette and 1 as the filter's maximum vignette size. Vignette Sharpness controls edge feathering; higher values sharpen the falloff but do not turn it into a hard matte.

Effect Mask remains a normal Fusion mask input that gates the entire PrismBlur operation. It is not the same mechanism as the internal Vignette Size/Sharpness controls.