Why they are slapping the steadicam when filming

Soon after I viewed generating of Star Wars (2009 or whatever) plus they were exhibiting the way in which they shot it. I observed one thing strange

They'd your digital camera film the stars (may are actually steadicam, dunno) and there exists 1 man that keeps slapping the rear on the steadicam each and each individual shot. He just keeps pounding about the rear of this region in which the film might be put inside your digital camera.

What is going on with this?I didn't have it until finally unquestionably one of my buddies told that:

"After I shot on film in Euro we accustomed to smack the rear of your LTR (16mm cam) anytime it may start out creating noise. Should really you smacked it, the film would fall back to location and become quiet."

Ah,it' humorous.Specifically what a naughty steadicam!