Since I've been reading up on automated lighting, I've been confronted with the term "indexable gobos". What is gobo indexing? Also, what do prisms do in an automated light?
I assume you mean indexable goborotation - this is where instead of just having "clockwise at # speed" and "counterclockwise at # speed" you also have "go to this degree of rotation form an arbitrary zero point" - this is good for designs where you need a specific orientation in a rotating cue.
Prisms are after the gel and gobo wheels and usually give you multi-image effects.
