36 FPS 4K widescreen conformed to 24fps?

[Jack Allred]

I am shooting a music video this weekend and can't decide if I should plan on 4kws 36fps, or if I should stick with 3k 48fps.

Lots of ballet dancing in the frame.
48fps is plenty, I don't need 60fps.

I'd like the wider FOV with 4kws, but:
1. I'm not sure how well 36FPS conforms to 24FPS if the director wants to keep certain shots in real time.
2. Also not sure how slow 36fps is in a 23.98 timebase.

I saw "Dig into Waves" but I can't judge on that because there are no people, and it's a mix between 60fps and 36fps so I can't be sure which shots are which.

Any advice or examples out there regarding #1. and #2.?

Edit: My camera is out on rental until tomorrow night (the night before the shoot) so I can't do my own tests.

 

[Josef Gatti]

Probably not what you want to hear (or say to the director), but I would get the director to decide prior to each shot, and storyboard which shots are to be in slow motion. If he can't decide, I'd shoot those specifics shots twice. But that's me

 

[Jack Allred]

Thanks Josef. You're absolutely right.

 

[Mike P.]

I know you don't have time, but the test could literally take 5mins... Worst case, if 36fps turns out to not be slow enough, you can leverage software (twixtor, AE, optical slow mo) to slow the footage down even further (an additional 20% or so should be easy).

Conversely, if you're finishing in 1080p, I can't imagine 3k not being enough quality.

 

[Jack Allred]

Thanks mike,
I was able to use a friends scarlet to test 36fPS vs 48fps, and 36fps actually works better for te style and tone of the piece.

So the remaining question I have is what time base to use? Will it be easier to edit 23.98 time base or 36.00 base? If the director doesn't know what shots she wants sped up or slowed down on set, I'll just going to shoot everything at 36 frames per second on a 23.98 time base. Will the editor have a hard time with that? I cant ask the editor because currently the editor has not been chosen.
Basically: will it be problematic to conform 36fps to 24fps if the director ends up not wanting any slow mo shots?

 

[Mike P.]

Probably better to go 23.98 timebase and then have the editor speed up the clips to play real-time if the slo-mo is no longer wanted (e.g. playback the 36fps stuff at 150% and it'll be regular/real-time/24fps). Especially if you're going to be shooting the rest of the stuff in 23.98 anyway. BUT, that could just be me thinking that since a 36 base is not a standard, it seems overly awkward.

I mean, it's a music video, so you don't have to worry about audio, which is good. Also, with all the unknowns, I'm starting to think Josef was right in suggesting you shoot the necessary shots in both 24 and 36...

 

[Jaakko Rinne]

Yep, set your project to 23.98/24fps timebase and for the overcranked shots shoot varispeed at 36. I don't think it would make any sense at all to try to work at 36 fps as your project framerate. If the editor wants an overcranked shot to be normal speed, they can speed it up to 150%.

 

[Jack Allred]

Thanks everyone! I shot today at 23.98 timeshare, even when shooting 36fps. I'll let you know how post goes and put the video up here when it's done.

 

[Nathaniel Opgenorth]

If you remember to post the final product that would be great! 36fps has always been a curiosity of mine since I think 48 is great (but not for everything) while 24 might be a bit too much for certain scenes and I much prefer shooting in multiples of 24 since I use a 23.98 timeline like 90% of the time (so 24, 48, and 120fps so far but want to try 36 out). Man if all media content was in 24, 36 and 48fps I think I'd be okay with that! No PAL or NTSC issues

 

[Jeffery Anderson]

the simple logic behind highspeed recording, if you're playing back at the same speed, is that the motion artifacts will be less.

From what I've seen; explosions, fast moving vehicles, general movement of the world/camera will feel more realistic or natural played back at a higher speed...

Only example I can thing of, off the top of my head is from Death Proof/Vanishing Point. I believe a lot of the stunts scene were shot undercranked, then sped up to normal speed. similar to what they did with Saving Private Ryan and the shutter speed.

...so I imagine that slowing down highspeed footage would look smoother and more elegant...video games have made most audiences expecting something different, or similar...guess it's what generation you grew up in.