Fps, shooting slowmotion in musicvideo

[Red october]

Hello.

Can somenone answer this?


I´m gonna shoot a music video this weekend.

I want this slowmotion effect of performance.

The band is playing their song in say 130% speed on set, and in postprod you can sync it to normal speed.

I wanna shoot in 4k. How many fps can i shoot then? 32?

If i shoot in 32 fps, is it right that the band should play their song in 130& speed during shooting?


Danny

 

[David Birdy]

Hello Danny

If you are after FAST frame rates you will want to Scale to 2K 100 FPS @ 16x9 & 120 Frames per second @ 2:1.

Dave

 

[Andrew Walker]

If your shooting with the band playing back at 130% then you should shoot in 3K as that's a good split between fps and resolution.

 

[Stefan Scherperel]

It sounds like there is alot of guessing going on. When shooting for a slow motion performance, if you want the performance to match the final playback of the song, you must shoot at the proper framerate that matches the % of speed that you sped up the song.
We just shot a music video using this technique and these are the speeds we used.

shot at 4K 30fps we sped the song up 125% (30fps is 125% the speed of 24fps)
shot at 3K 36fps we sped the song up 150% (36fps is 150% the speed of 24fps)
150% was the fastest that the musician could actually perform the song, as it's a rather high tempo song. For slower songs you may be able to perform the song even faster. I gave the artist the song sped up to 150% a week before the shoot so that he could practice.

If you simply choose a random percentage to speed the song up, then shoot at whatever frame rate you want your going to end up with synch issues in post. While you may be able to pull off 1 or 2 seconds at a time anything longer will go out of synch.
And make sure you let the band practice with the song before hand, or you will end up with synch issues as well, when the band can't perform at the speed you are pkaying back the song.
As far as what resolution to shoot. Well
4K up to 30fps
3K up to 60fps
at 60fps your playback speed would be 250%. I think you'd be hard pressed to find anyone who could perform a song at that speed.

Here are our results.

http://www.youtube.com/watch?v=VnzaPkl6Nvg
or
http://www.vimeo.com/3695973


By the way, to answer your original question, 32fps is 133.33% of 24, so that is what you would want your song sped up to. although at 32 fps you are limited to 3K, so if you wanted to shoot at that speed I would recommend going back down to 30fps, song at 125%

 

[Red october]

Thanks for useful info!

Stefan: am i misunderstanding, but isn´t european cameraes shooting in 25 fps normally, and american cameras 24 fps?

If that so, does it matter, or can i still use your diagram for right synch?

 

[Stefan Scherperel]

If your time base is set to 25fps, then yes the math will be a little different. The red can shoot with either time base, so there shouldn't be an issue. Here is the equation you can use to figure out what percentage you need for song playback at whichever framerate you choose.
Desired framerate = DF
Standard framerate = SF

DF/SF= Playback speed %

So 30fps / 25fps = 1.2 or 120% speed increase
35fps = 140% speed increase
40fps = 160% speed increase

We found that like Andrew pointed out 3k is a good mixture between framerate and resolution so you may see if your artis could perform the song faster than 120% and up the framerate.


One note to all those ntsc users, my percentage speedups listed above are not 100% accurate because we were shooting at a 23.976 fps timebase, hoever fopr a 3:20 song, the shift was not noticeable, if you want to be more accurate use 23.976 instead of 24 in your calculations.

 

[Red october]

Thank you so much Stefan.

Very useful info.

Kind regards.

 

[Kwan Khan]

For EX:
To shoot 48fps slow motion for a 24fps timeline = 2:1 slow motion. Speed up the track (2 minute song and speed it up so that it plays for exactly 1 minutes). Have your Artist lip-sync to speed-up version of the Track.

18 fps: make song last 1.333x longer by stretching it to 75.0% speed
20 fps: make song last 1.226x longer by stretching it to 81.6% speed
22 fps: make song last 1.067x longer by stretching it to 93.7% speed
26 fps: make song last 0.907x as long as normal; play it at 110.25% speed
30 fps: make song last 0.800x as long as normal; play it at 125% speed
32 fps: make song last 0.747x as long as normal; play it at 133.87% speed
36 fps: make song last 0.672x as long as normal; play it at 148.81% speed
48 fps: make song last 0.498x as long as normal; play it at 200.80% speed

One note to all those ntsc users, my percentage speedups listed above are not 100% accurate because we were shooting at a 23.976 fps timebase, hoever fopr a 3:20 song, the shift was not noticeable, if you want to be more accurate use 23.976 instead of 24 in your calculations.

Agreed