This is a camera Frustum object and it’s meant to be used as a field object in Cinema 4D. It’s a bit experimental since it’s not truly field object. Basically it’s just a polygon object shaped as a quadrilateral frustum. Polygon object’s points are connected to match linked camera’s view frustum with Python Tag. There’s a couple settings to change: Distance of near plane and far plane, also option to adjust width and height padding.

Drop Camera Frustum object to effector’s field list and set the ‘Mode’ to ‘Volume’ to make it work as designed.

ar_field_camera_frustum.c4d v1.0.0 (2023.2.0)