Steven Soderbergh struggled with the iPhone's selective focusing while shooting his latest stalker thriller 'Unsane'.
The 55-year-old Academy Award winner is the latest filmmaker to helm a movie using the handheld mobile phone device, but despite claiming he didn't have any problems with the battery, he admitted the focusing caught him off guard, but he had to work his way around it.
In an interview with the Metro newspaper, Soderbergh said: "The [iPhone's] selective focus issue is something I just had to work my way around.
"The sensor's very small, you have incredible depth-of-field and have to orient yourself towards things that take advantage of the fact everything's in focus, for the most part.
"We had no technical issues at all. I never lost anything. I never had dropouts. I never had a battery problem."
The new film - which stars Claire Foy and Juno Temple - follows Sawyer Valentini [Foy] who moves from Boston to Pennsylvania to escape a man who has been stalking her for two years.
While meeting with a therapist, Valentini signs in for a voluntary 24-hour commitment to a behavioural centre and during her stay doctors and nurses begin to question her sanity.
Valentini starts to believe that one of the staff members is in fact her stalker and will do whatever it takes to stay alive and fight her way out.
Soderbergh - who is married to Jules Asner - decided to shoot his latest movie using three iPhone 7 Plus devices after being inspired by Sean Baker's 2015 film 'Tangerine' and said it let people know where technology was heading.
He said: "That let people know where this technology was heading.
"When you show that on a big screen it looks great because of the resolution."