I've always shot with a small crew, generally 2-3 people, on Beta SP in the early days, later an HVX-X200, then a Canon 60D & GoPro for a documentary feature two years ago. But I'm considering a personal documentary, one in which I'd like to be as unobtrusive in shooting as possible, and I've been considering an iphone (7, 8, X?) with and without a DJI Osmo Mobile gimbal.
I'd welcome any opinions from those who've tried such an approach or similar one.
iPhones with extra software apps to control them, like Filmic Pro and others, can give phenomenal results. Some issues they will have include needing external power, and over-heating, as well as having sufficient memory space.
And you still have the issue of needing to hang a lav or a shotgun mic to get optimal sound.
I don't know if they are less obtrusive than a DSLR or goPro type 4 k action camera, or a more conventional camera shooting from concealment on telephoto.
Unless you mean you're sticking the iPhone in a chest pocket and having the lens peek out over the top?
No, I don't generally need to hide my camera, though my GoPro does work that way. I like that I don't look like I'm making a film when shooting with an iphone (unless of course I rig it with lots of gear) but even more important is that I always have my iphone with me.
I haven't fully researched it but I've seen—somewhere—pocket drives that allow offloading an iphone. The heat problem I didn't know about. And then there's the problem of color grading and correction.