Better to change the light to a spotlight, then parent it to the ball, then convert back (if needed) to infinite. You can't parent an infinite light directly. If it is an infinite light, only the rotation settings of the ball will influence the light, translations won't The idea of attaching a node to the light in the material is probably the way to go. As far as I know, it's not possible to put a filter on a camera. You can play with the depth of field settings, depth cueing settings and motion blur though.

The pen is mightier than the sword. But if you literally want to have some impact, use a typewriter

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