BERLIN • Director Steven Soderbergh (above) has a new calling. On Wednesday, he said he so enjoyed making his psychological thriller Unsane on an iPhone that he would find it difficult to go back to conventional film-making.

Unsane, premiering at the Berlin film festival, was shot over just two weeks - way shorter than the months a movie usually takes.

It tells the story of a woman (played by Claire Foy) who moves to a new city to escape her stalker, but finds herself admitted to a mental health institution where he works.

Soderbergh said the overall experience of making a film on an iPhone was good, though there were some drawbacks such as the phone being very sensitive to vibrations.

"I have to say the positives... really were significant and it's going to be tricky to go back to a more conventional way of shooting," he added.

Not having to make a hole in a wall or secure a camera to the ceiling are big advantages, as is being able to go straight from watching a rehearsal to shooting, Soderbergh said.

"The gap between the idea and execution... is just shrinking and this means you get to try out more ideas so I wish I'd had this equipment when I was 15," he added.

Unsane is among about 400 films screening at the festival, but is not among the 19 vying for the main prize, the Golden Bear, which will be awarded tomorrow.

REUTERS