Fast motion in camera or in post?

[Jason Gallagher]

I am the editor on a film being shot on the RED. The director is wondering whether he should shoot fast motion (18fps or lower) for action (car chases, fight scenes, other action) or if we should modify the speed in post.

Has anyone had experience with one or both scenarios? And if speeding up footage in post, is FCP the ideal way? Or in a more hi-fi post situation (ie Flame or Smoke)?

I would love to see some footage examples if anyone has links...

Thanks for your help!

Jason

 

[Jonathan Stevenson]

I suggest shooting slower frame rates. It looks a lot cleaner than just speeding up the footage in post. But, if you DO end up speeding it up in post, Motion has a lot better frame rendering engine than FCP for speeding up or slowing down footage.

My two pesos!

 

[michael zaletel]

Couldn't you just shoot at say 36fps and then use every other frame so that you aren't dealing with any calculated frames? Then at least you'd have the full motion if you want to do any retiming effects. Anyone try this before? Any problems with the approach?

-shooter

 

[Peter Karlsson]

Try http://www.revisionfx.com/products/twixtor/

It works with FCP aswell I think.. IF you shoot 18 fps, and it doesn't look good what are you going to do then? Better/safer to do it in post.. Twixtor will calculate motionvectors, so you can try out different speed with great results.. No need to jump into a highend suit.

 

[Brandon Fraley]

the reason to do it in camera is you have control over the shutter. if you shoot normally and then change the speed in post, you wont get the shutter to match whatever framerate you've chosen.

 

[Jason Gallagher]

i think the twixtor program looks best out of all the options. we are looking for the greatest combination of control and quality.

brandon, can you expand on your framerate point? won't the programs that speed up/slow down the footage account for framerate and adjust accordingly? or at least make it look the same?

thanks for the input...

J

 

[Brandon Fraley]

brandon, can you expand on your framerate point? won't the programs that speed up/slow down the footage account for framerate and adjust accordingly? or at least make it look the same?

thanks for the input...

J

Different shutter angles change the way the motion looks. The unspoken rule is, unless you have a specific reason not to, to always shoot with a 180 degree shutter.

If you shoot 24fps with a 180deg shutter and then speed that footage up twice as fast, you are also in a way changing the shutter, dividing the exposure time in half, which changes the look.

just to continue this example, if you knew you were going to speed the footage up 2 times in post, you would have to shoot with a 360deg shutter to get the presumably desired 180deg look in post.

The point being, instead of figuring out the math, just choose the framerate you want and shoot it in camera. That way you can control over everything about the shot.

If you don't know what framerate you want, then twixstor is a good app.

 

[michael zaletel]

the reason to do it in camera is you have control over the shutter. if you shoot normally and then change the speed in post, you wont get the shutter to match whatever framerate you've chosen.

Good point Brandon.

-shooter

 

[Craig W. Bickerstaff]

I'm with brendon, in camera is the best way to go for this.