Another interesting bit of ILM film up for auction. The original ESB emperor, with a bit of camera slate apparently showing the tv monitor the footage was rephotographed off of to get the hologram look.
http://www.ebay.com/itm/Empire-Strikes-Back-EMPEROR-FILM-ELEMENTS-Lucas-Director-Slate-1980-Film-Clips-/171395850849?pt=LH_DefaultDomain_0&hash=item27e7fd2261