Hi Brad and welcome to the Q&A Board. While it's not exactly "real time" (a picture must be taken first) but Canon has software for using a camera (Canon of course) tethered to a computer. I am also assuming we are speaking of digital cameras here.

I would expect your pros would have the software already though I'm not sure if
EOS Capture is part of the standard software utilities package.

I'm afraid I haven't tried to use the software so I can't give you first hand knowledge. Perhaps someone who has will stop by and add a bit more info.