Variable speed within the same scene

3

3xm

Active member
Hi,

I was wondering how to achieve a variable speed change within the same scene. For example in a movie you often see a guy walking at normal speed...and then suddenly an explosion happenS behind him and the whole scene looks like he's moving slower and makes it more dramatic. Same example with car commercial...where a car is moving aT normal speed and it drives over a water puddle and the whole sceen palys in slow mo. How is it this done without using slowmo built in the the editor (which never looks good).

I guess what I am asking is can I overcrank the HVX200 to shoot at higher speed (say 48 or 60) and then import that mxf/avi and have part of it play at normal speed (48/60) and other part of the clip play at 24f (which will then make it play slower)?
 
Sure, set your rec speed at 720 24p and in your scene settings set to rec at 60fps then depending on which editor you use you can speed the footage up to normal speed in certain spots (ie, add edits to you clip in your timeline) and have other parts play slow mo. There are some limits to it but you can get a pretty cool effect if you speed your faster parts up even faster than normal and end up with the MTV cribs effect.
 
If I know I'm going to ramp speed within a given shot, I typically shoot it at normal speed and use the ramping (Velocity Envelope in Vegas) within the NLE to achieve it.

You have infinitely more control this way, setting velocity changes within frame-accurate parameters and levels.

I've had good luck with 24 frame acquisition ramped in the NLE to odd speeds without strobing, while others (using different applicaitons) report strobing when they do the same.

30pfps and 60i should give you smoother results for post-production induced ramped effects.

Conversely, we set up lots of time-lapse and slowmotion with the HVX, because the rates are relatively easy to change when you know you're going for a look.

Like anything, if you know you're going for an effect prior to shooting, it makes the in-camera versus in-post decision much easier. In reality television we rarely if never do slow-motion in camera, but always shoot timelapse in camera now.

For documentary, I tend to do plan more slow-motion and certainly time-lapse in advance, which might achieve better results, but somewhat also limits your choices or flexibility for the same footage in post (e.g., in-camera synchronous sound).

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i say shoot a 60p but on like 210d shutter in 24p mode and then ramp it faster inyour NLE. shooting in 60p will give you all the information you need, extra freames and all to make it look silky smooth
 
In filmcameras you can change the speed with special motors. I used one once and it is awesome but needs quite some planning as to when exactly go for slow and when not. But it works.
In the HVX i would shoot 50p/60p and then speed up when needed. It looks better to to play 50p at 25p than the other way round.
 
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