Matti Haveri wrote:
…
Some respectable sources claim that only animation is 30 fps, and all other devices are really 29.97 fps although they report it as 30 fps.
wow, who am I to contradict sensei Tom 😉
but…
(the following is all btmk, and I don't want to ignite a 'who has he better links'-contest)
29.97 is for interlaced. You frequently read that as '60i' - 60 fields. Almost sixty…
30 is for progressive; and I don't know, how Tom deduces that 'none' camera shoots 30p, but 'secretly' 29.97 (I or p) And outside US, the story is different again: ALL cams, I used and using shoot 50i or 25p or 50p - and 25 as 25, not 50i. Manufacturers as Panasonic explicitly declare in their tech-note 'sensor read out by 25/50fps' …
Back to your recording session - bad news first:
iPhones deliver out-of-the-box 'anything' but just sometimes 25/30fps!
That's because, they don't own an aperture nor a gain (aka 'ISO'), so under low light conditions, poor Phony can adjust exposure only via shutter-speed => which effects frame-rate, when you reach <1/50th res. <1/60th sec.
In tools like MediaHud you can dramatically watch 'variable frame rates' resulting into '20.73 fps' or wotever - which makes FCPX some hiccups (consumer toy iMovie is more tolerant…)
In some of my projects, I crudely mix all sorts of frame rates – never noticed a 'dropping every nth frame'-cadence, but my cold stiff eyes 😉 … what I notice is stutter, when using too high shutter speeds. Or when panning like using a vac cleaner LOL
Last word about interlaced: only tube-based displays can playback I-footage (=based upon afterglow); ANY modern flat-screen (plasma, led, oled) needs tons of sophisticated electronics to 'calculate' the frame out of interlaced video - flatscreens have no 'fields'. So why recording in i anyhow?
Last word about flicker: lately recorded in an exhibition, they used LED-lights = creates inch-wide lines when you set exposure too fast! So, 30fps vs 50Hz AC is less the problem than those energy-saving but too fast 'blinking' modern lights …
tl;dr:
if your Canon allows only 25p, keep that as standard. Set phones to 25 if optional, avoid low light situations, avoid high angular speeds (subject or camera) in bright light situations. Consider rate-conforming if you notice lost-frame-cadences. Consider 3rd party tools to force phones to constant frame rates .
… btw: there are 'hacks' to switch European cameras to US, offering then 30fps - but what you said about 50HZ-lights…
…. best to my knowledge, pretty sure, I'll stand corrected in a minute 😉
And if you want more brain-hurt - odd 29.97fps vs integer 44.oooHz audio-samplerate (known as audio-shift in longer takes)? And what about 23.98fps aka '24'? UHD is 60fps … sometimes 48fps, AC is 50. -
keep it simple, 25p, 30p. if drops noticeable, conform. done.
