"It's about time someone preserved the images of a generation of fantastic tale spinners," writes Jerry Pournelle about the idea for The Faces of Science Fiction photographed by Patti Perret (Bluejay/St. Martin's: $11.95). Eighty-two authors supplied a message for the page facing their own picture. They compliment readers, other writers, and themselves. Marion Zimmer Bradley sums up what she sees as the strength of the genre: "SF encourages us to explore . . . all the futures, good and bad, that the human mind can envision." The best-known authors are here--Ray Bradbury, Isaac Asimov, Frank Herbert--but so are Diane Duane, Manly Wade Wellman and Somtow Sucharitkul. Two or three in the group look like the old stereotype of the SF fan : chubby, wispy beard, thick glasses, a manic glint in the eyes. Perret's informal black & white portraits are appealing, the text is lively and enjoyable.