I also watched the last half of THE SINGING NUN.
I had forgotten that this was a BIG MGM reunion film with all of the major actors from MGM's golden days: Debbie, Greer Garson, Agnes Moorehead, Ricardo Montalban (who looked GREAT), and Tom Drake. (Had forgotten Katherine Ross was in it, too, as well as the always wonderful Juanita Moore.)
This was shot in Panavision, but looked more like early Cinemascope in 2.55:1 aspect ratio. It was VERY narrow.