Hollywood Musicals, by Ted Sennett. New York: Harry N. Abrams. 384 pp. $ 50.
For a loving look at a half-century of ''uniquely American .... exuberance and optimism,'' this book is a delight. It traces the history of the American musical film from the original ''Jazz Singer'' of 1927 to its 1980 remake, with stops along the way for individual chapters on Fred and Ginger, Mickey and Judy, and crooning Bing.
With 450 illustrations to 360 pages of text, the emphasis is on the magic that's been captured in front of the lights. But author Sennett has plenty of backstage whispers and chuckles to pass along, as well.