This is technical and less precise than plugins, but it costs $0 and uses zero external files.
The most common reason Lens Blur appears "missing" is due to your project's color depth. If you have set your project to , the standard Lens Blur effect sometimes refuses to apply or causes a crash. In older versions of AE (CC 2017 and earlier), the effect would simply vanish from the menu.
: If the effect is present but not visible, ensure that Draft 3D is turned off in your timeline panel, as this mode disables depth-of-field and certain blur effects to improve performance.
If even the new Camera Lens Blur is missing from your menu, it usually points to one of three things:
