Hello. I would like to know how to turn on some kind of indicator that will show me exactly how much of the image in a given camera view will be rendered.

Like just an outline or box overlay that will show me the border of the area of the real-time view that will be rendered so I can actually set up my cinematography without having to guess what I'm going to get when I render.

The indicator would obviously need to be a different shape if I was rendering in 16:9, 4:3 or some other aspect ratio. Does anybody know what I mean?

I'm sorry for asking this if it has been answered already, but I couldn't figure out what to search for to find out if it had.

Thanks a lot.