Complex sentence: The series followed Connors'highly popular series "The Rifleman," but it did not have that show's longevity, lasting only 48 episodes over two seasons, the first in black and white, the second in color.
Split into simpler sentences: The series followed Connors'series "The Rifleman", but it did not have that show's longevity, lasting only 48 episodes over two seasons. The first season was shot in black and white, the second in color.