John C. Mahon Jr., an educator who served as one of the original professors and lecturers at UCLA’s Motion Picture Department and later at NYU, died Jan. 14 of respiratory failure at Orange Hills Convalescent Hospital in Orange, Calif. He was 79.A native of Schenectady, N.Y., he served in the U.S. Army as an officer during World War II. Following the war, he received a Masters in Theater Arts from UCLA. Throughout his long and distinguished career, Mahon was involved in hundreds of theatrical, TV, educational and industrial productions. He was also a member of the Academy of Motion Picture Arts & Sciences. He is survived by his sister, five children and six grandchildren.