GH3 Two VERY Stupid Questions

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Ianscreations

Well-known member
I apologize in advance for asking two questions that is probably something I should know:

1) Tonight I experimented with shooting my GH3 at 24FPS and my EM1 at 30fps. After 24 minutes, both cameras were still in perfect sync. How can this be? How can two cameras shooting at two different frame rates remain synchronized?


2) I know how to shoot 60fps and reduce that to slo mo. But how do you do the opposite? If I want to shoot something in a way that I can opt to speed it up smoothly, what method do I utilize? Say I want a shot of a baseball player hitting a ball in regular speed. Then he suddenly rounds 1st and 2nd in super fast motion and then resumes regular speed as he rounds third and comes home. How do I achieve this? Just shoot my preferred frame rate and speed it up in post? Do I need a specific shutter speed for the associated frame rate?

Thanks!
 
Err, because filming isn't like travelling at light speed, and relativity doesn't come into play?

You can drop frames. Just shoot as normally.
 
The 2 different frame rates won't make any difference to sync unless you play them back at the wrong speed. Meaning if you conform 24P footage to play on a 30P timeline then it will be going at a higher speed. The same goes for putting 30P footage into a 24P timeline - it will be a little bit slo-mo.
But if they are both shooting their own number of frames per second - well the length of a second doesn't usually change here on Earth.

Speeding up footage is usually done with the playback speed control on your editing software - and it looks sped-up.
TWIXTOR may be smoother, I haven't ever used it for anything but going slower.
I suspect that if you shot at 30P and put it into a 60P timeline it would technically be smoother (maybe) but it would probably look just the same.
 
The only reason I ask about syncing is because I've shot live events before with two different brand of cameras (Canon and Sony) at the same frame rate and they loose sync over time. So I am shocked that two separate brands shooting at different frame rates actually stay synchronized.
And I'm not sure I asked the "fast motion" question correctly. We all know that a great way to shoot slo mo is to shoot 60 fps with about 120 ss and slow that down in post. But how do you film the reverse? Say I want to film something that I will speed up in post....what framerate should I film the action with/what shutter speed should I use?
 
I would "Speed it up in post". In my editor, I grab end and shrink the clip and it is sped up. How it was filmed does not matter at that point, since it WILL drop or blend frames to make it faster.
 
The whole sync thing. It's coming from the internal clocks of your different devices, not from the frame rates of the cameras. That's why two different cameras at two different frame rates just so happened to stay synced. Often one external recorder at 48khz will drift off from one camera also recording audio at 48khz... It's the minute differences in their internal clocks drifting off over time. That's why ideally you want sync-lock either between two devices, or being controlled by an external time code master source.
 
Ianscreations said:
I've shot live events before with two different brand of cameras (Canon and Sony) at the same frame rate and they loose sync over time.
Click to expand...

That's not normal. I've shot a LOT of multicamera events using different brands (including Sony and Canon), and they've always stayed in sync.

This is why audio recorders frustrate me so much. If cameras can maintain perfect sync over an hour or more, why don't all audio recorders do this by default? I should not have to adjust the speed or my seperately recorded audio to keep sync with any cameras, all these devices should naturally be running in perfect sync.
 
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