How to do slow mo?

M

markinhifi

Well-known member
I had a hell of a time learning how to do this correctly on my HVX and now the process starts all over again..

Ideally i'd like to shoot at 48p, but since that seems to not be possible with this camera, i'd settle for 60p... So, I shot something at the 1280/60 setting, and the shutter speed indicator in the corner says 60.

So, I transferred the video to the computer, converted to ProRes and dropped it into a 23.98 timeline. However, it's playing back at normal speed. If I did this with my HVX footage, it would have automatically slowed down. Is there a different process I must go through now to get it to slow down properly? If I just make the speed 50% it looks horrible, that can't be right.

Question #2- If i'm trying to shoot a music video in slow motion.. What would I have to speed the playback of the song to (on location) in order to lip synch, and have it come out correct speed once in final cut?

And also, is it not possible to shoot lower than 24p on this camera? What if I wanted fast motion, is that not possible either?
 
#1 Stretch it to %40 speed.

#2 Unless you use a 30fps timeline, you're going to get ghosting/blended frames trying to use any 60fps clips in a 24fps timeline EXCEPT for at %40. Now CAN get away with faster/timelapse but you need to do it in multiples of 2. 2x, 4x etc.....

It's all about the math and getting whole numbers of frames.
 
kidwoo said:
#1 Stretch it to %40 speed.

#2 Unless you use a 30fps timeline, you're going to get ghosting/blended frames trying to use any 60fps clips in a 24fps timeline EXCEPT for at %40. Now CAN get away with faster/timelapse but you need to do it in multiples of 2. 2x, 4x etc.....

It's all about the math and getting whole numbers of frames.
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I just tried putting it in a 24fps (and 23.98) timeline at 40% and i'm still seeing blended frames.

What about 50fps? Would that be easier?

For fast speed I just tried playing music back at 50% speed recording it @24p, then dropping it into a 24p timeline and making the video 200%. That came out fairly well.. But it seems like slo mo will be a problem.
 
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Shoot 720 60p or 50p . convert to prores. You then have to conform each Pro res clip to 23.98 in Cinema Tools then drop in 23.98 timeline. Cinema Tools comes with FCP.
 
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markinhifi said:
I just tried putting it in a 24fps (and 23.98) timeline at 40% and i'm still seeing blended frames.
Click to expand...

That shouldn't be happening. Go frame by frame and see how freqent the blended frames are. I've had one or two pop up in like a 10 second clip but the majority should be full progressive frames.

What program are you editing with? Do you have a frame blending option that's checked by default? Premeire Pro does this.


50fps won't do anything differently....unless you're in a 25fps timeline, then you can go %50 obviously. You COULD go %48 with a 50fps clip in a 24fps timeline.
 
Also if you like 48fps slo mo you can change the recording format to Pal on the the 7d which will then let you shoot at 720 50p which is close enough to 48.
 
Right, just be aware that the PAL frame rates are based around the actual speed (i.e., 50.000 fps) and the NTSC frame rates are 0.1% slower (so 24fps = 23.976).

So if you use FCP and can conform the 50fps footage to 23.976, all should be good. But if you're trying to time-stretch it, you'd want to stretch it to 47.952% of its normal running speed to get accurate slow-mo (not 48%, like you might otherwise think).
 
kidwoo said:
That shouldn't be happening. Go frame by frame and see how freqent the blended frames are. I've had one or two pop up in like a 10 second clip but the majority should be full progressive frames.
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See how your method is flawed? You should not have any blended frames. That should be unacceptable.

If you use Cinema Tools's "Batch Conform" function, you'll have perfect slow motion without any blended frames. Plus, you won't have to render the effect. The conform function merely rewrites the file header to indicate that the clip should be played at 23.98 fps instead of 59.94 fps. Note that Batch Conform will want to conform all of the clips in a folder, so you'll want to move the clips intended for slo-mo to dedicated sub-folder first.

Also, slo-mo should be shot at 1/120th (or 1/125th) shutter to approximate film-like slo-mo. 1/60th has too much motion blur compared to proper slo-mo on film.
 
mico said:
Shoot 720 60p or 50p . convert to prores. You then have to conform each Pro res clip to 23.98 in Cinema Tools then drop in 23.98 timeline. Cinema Tools comes with FCP.
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This worked perfectly! Thank you.

Now, any math geniuses know what i'd have to speed the music up to when playing it on set in order for it to play normal speed in the timeline??

So i'm shooting at 60p, then slowing to 24p. So the music would have to go from what % while shooting to 100% in post?

EDIT: Found this post by Barry: http://www.dvxuser.com/V6/showpost.php?p=891871&postcount=5

60 fps: make song last 0.400x as long as normal; play it at 250.00% speed

Going to try that out.
 
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Okay, I took 50fps footage and converted it to 23.976 but it seemed to end up slightly slower than that as the audio sync between the recording and the wav i have in the timeline seemed to drift apart after a few seconds.

Is that normal?
 
No, you're mixing two things that I was saying. If you "conform" the footage using Cinema Tools, then I believe you could just drop it on the timeline and it'll work with no frame blending or problems.

But if you used 50fps, then 250% speed is wrong. You'd have to calculate the speed differential between 23.976 and 50.000, and speed up the music according to that. 250% is the right speed for when using 60fps, but not for 50fps. For 50fps in a 23.976 timeline, you'd need to speed the music up to 208.54% speed. (50/23.976)
 
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