"Danny Boyle told IndieWire that despite the iPhone having image quality and resolution that is now suitable for a major motion picture, there is a misnomer that that means anyone can make a movie with it. If anything, getting the iPhone to do what Boyle needed on '28 Years Later' required an even more skilled and experienced cameraperson than if he’d used a modern professional camera."
https://www.indiewire.com/features/craft/28-years-later-iphone-hollywood-movie-1235134798/