The psychological thriller stars British actress Claire Foy of the Netflix series "The Crown". Foy plays Sawyer Valentini, a woman who is convinced that a man called David is stalking her. She moves to a new city to escape him but finds herself admitted to a mental health institution where David works.
"It is an interesting turning point with regard to cinematography and what we see happening to digital cameras. The time calls for a change in the methods of filming, and I sincerely enjoyed that. I tried to find an advantage in the new way of shooting", Soderbergh told reporters on Wednesday.
The 55-year-old American director pointed out that using the new technology let him have more control over the process of film-making.
"(Shooting on iPhone) provides many advantages. I can place a camera wherever I want within seconds, and there's no need to attach it to a wall or a ceiling… The ability to shoot scenes fast boosts the energy of the whole process. That said, small devices are much more sensitive to vibration", the director admitted.
Despite minor hiccups, Soderbergh said he enjoyed filming on iPhone and would find it "tricky" to go back to a more conventional way of shooting.
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"The problem was always there", he explained.
Soderbergh is known for his eagerness to play with genres and formats. His recent HBO series Mosaic was released last month on television and as an interactive mobile app, allowing the audience to choose from which perspective they want to watch.