Weird question about shooting 50FPS on DSLR and singing

[BrenMyster]

Hi

I will try to explain this with out sounding overly complicated. I can't get my head around it.

SO I have just got a nikon d800 and I'm shooting a music video next week. Like most video I do I want to shoot a few takes where the song is sped up 50%. I usually shoot on a sony f3 and then when we do the fast take I set it to 36FPS (i'm on a 24p time line here) so the singing is being recorded 50% slower. Then when I drag everything in to FCP it all works because I have final cut set on a 24p time line. perfect, and easy.

Ok, so here is my thinking, since I can't get the d800 to shoot 36fps I will shoot everything 25p timeline, then when I do the slow mo stuff I will shoot it 50p and then speed it up to 150% in FCP. In my head that should work out. The song is 50% faster when the video is 100% slower so in FCP speeding the video up 150% should make it all work.

Now I have just tested it and the only way I can get the song to sync with the video is by speeding the footage up to about 134%, this is very weird, why 134? and it will got out of sync after about 30 seconds.

Any help would be good

Cheers

b

 

[Amr Rahmy]

when you say song is sped up 50%, does that mean +50% as in the song is 150% from original. 1/3(+1/3) faster.
and then you slowed the movie by 1/3(-1/3) shooting 36 to 24.

going from 50 to 25 is half, -50%, or 50% from original, (-1/2)
you could change the audio accordingly and not mess up with other variables.(you did not mess with other variables in the first example, don't start now)