Sync problem when shooting at 12fps over 24PN

[ksteiger]

Shooting a music video and I want to shoot at 12 fps in 720 24PN mode. If I play the music at exactly half speed while shooting, I should end up with the action in sync with the real time music upon playback, right? Well???

It seems to play back a tiny bit too slow. (As if it were shot at, maybe, 13 or 14 fps.)

I tried a simple test. I shot at 12 fps while simply clapping to the tune at actual speed in quarter notes. Playback confirmed that the footage was running slightly slow. It would start OK but then drift out after 6 to 8 seconds.

I tried a similar test at 48 fps. I clapped to the tune in real time in eighth notes. Playback was similar in that the quarter notes started lagging after 15 seconds or so. (Like maybe it was shooting at 50 -56 fps)

I know that I have the settings correct and am verifying all this in camera and not my NLE (FCP) I first discovered the problem in Final Cut, however.

Does this make any sense? Any thoughts?

Am I unable to clap my hands in time???
No I think at least I have that much right.
Thank you.

HAPPY THANKSGIVING:beer:

 

[Barry_Green]

12fps is not 12 fps, nor is it half of 23.976 either. It's 12.26. So your results are exactly as to be expected.

Refer to this post to solve how to use the offspeed frame rates properly for the effect you're trying to accomplish:
http://www.dvxuser.com/V6/showthread.php?p=891871&posted=1#post891871

 

[ksteiger]

I did expect 12 fps to be 11.988 so this is extremely helpful, thank you Barry. How come every time i get an amazingly fast response EVEN ON A HOLIDAY it seems to come from BG?. I feel like I owe you a dinner.
Thank you Thank you Thank you.

 

[jjraabe]

I feel like everyone owes Barry a dinner... I sure do.