Based on his own fascination with spirituality, Aykroyd conceived "Ghostbusters" as a project for himself and John Belushi. The protagonists would travel through time and space to combat a host of demonic and supernatural threats. Following Belushi's death, and with Aykroyd's concept deemed financially impractical, he was paired with Ramis to rewrite the script to set it in New York City and make it more realistic. "Ghostbusters" was the first comedy film to employ expensive special effects. There was concern about the budget it would require and little faith in its potential for box office success. On an approximate $25–30 million budget, filming took place between October 1983 to January 1984, in New York City and Los Angeles, and on sets at Burbank Studios, Los Angeles. Competition for special effects studios among various movies in development at the time meant part of the budget was used to co-found a new studio under Richard Edlund. He used a combination of practical effects, miniatures, and puppets to deliver the ghoulish visuals.