From 1980: THE EMPIRE STRIKES BACK OFFICIAL COLLECTORS EDITION.
I had a copy of this at the time and I literally loved it to death. The cover parted company from the contents (the binding does seem suspiciously delicate so I suspect the damage wasn't entirely down to me) and the it became very battered and well-thumbed. But I loved it too much to take scissors to any of the extensive photos and illustrations.
This isn't that copy... I stumbled across it quite recently in a store along with a stash of other Star Age STAR WARS books (including all three "Art Of..." books)... which I considered quite a result.
Looking at this now I consider it to be something of the best-practice benchmark for this kind of publication. Not only does it relate the plot of the film (an ideal reference... if you didn't have the novel, comics, sticker album and, err, everything else) but it also has extensive behind-the-scenes material. All comprehensively illustrated with stills (some of which still seem pretty rare), production art and design work.
And that cover art still takes some beating...