Henry Joost and Ariel Schulman talk Paranormal Activity 3

Filmmakers Henry Joost and Ariel Schulman seemed the perfect choice to shoot the handheld horror Paranormal Activity 3 , given their previous work on Facebook documentary Catfish .

That choice paid off handsomely this weekend when the sequel - which cost just $5m to make - took an estimated $54m at the US box office.

That makes it the biggest horror opening of all time and the biggest October opening ever in the US.

So would Joost and Schulman consider Paranormal Activity 4 ? Studio Paramount is already talking up the possibility of a fourth film.

“There are definitely some unanswered questions at the end of this. We’ll see how it goes and how people react,” Schulman told Fangoria .

“These movies are sort of a response to the audience’s response, and a lot of it is built around what the audience wants. So if it feels like there are enough unanswered questions for us to come up with more mythology, then we’ll take a stab at it.”

The duo are currently working on another low-budget horror-thriller set in New York City.

“About all we can say is that it would be half found footage, and it’s about two teens in New York City. It would be pretty unique,” Schulman added.

As for their work on Paranormal Activity 3 , the filmmakers say they considered using VHS to give it the right look and feel for something shot 1988.

“But the studio wasn’t really interested in releasing a 4x3 analogue movie,” said Schulman with a laugh.

“We tested it, but it got pretty tiring to watch after a while. Everybody’s got an HD TV in their house, and movies look so great now - watching a VHS image would get pretty old fast,” Joost confirmed.

That problem was solved by using a filter on top of HD footage. However, many scenes show the camera operator in the mirror and for authenticity he couldn't be holding a HD camera.

“So we took a small HD lipstick camera and put it down the barrel of an old VHS camera, so when Dennis is taping himself and it looks completely like a VHS camera, it’s recording to an HD chip inside,” Schulman explained.