Setting the FPS Override for slow motion on Canon DSLRs

Started by Tyronetheterrible, January 06, 2015, 08:34:44 PM

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Tyronetheterrible

Hello everybody,

As I understand it, the common way to achieve slow motion with Raw video for Canon DSLRs is by setting the standard Canon menu to record 720p at 60fps, setting the FPS Override to 48fps, then slowing it down to 24fps in post.

So, does that mean that setting the FPS Override to a higher value like "60fps" as opposed to "48fps" would allow for an even slower motion?


Thanks in advance.

Datadogie

Yes. But I am not sure what over speed your camera maxes out at.
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Tyronetheterrible

Quote from: Datadogie on January 06, 2015, 09:29:40 PM
Yes. But I am not sure what over speed your camera maxes out at.

I own a Canon 6D. I will have to look into what the max over speed would be on this camera. Thanks for your help!

DigitalVeil

Yup.  48 to 24 is obviously a 2x slowdown, but you can stretch 60 to 24 for a 2.5x slowdown.  In Premiere, you'd simply put the 60fps clip in a 24fps timeline and stretch the clip by 250%.  You can can take any fps, even strange numbers like 63 or 79 and spread them out to fit exactly 24fps.

Here's a little video I shot just a couple weeks ago to experiment with slow motion:



I shot at 60fps, spread it out to 24fps, and then used Twixtor to stretch it to 12fps with interpolation.  Final result is 24fps with 5x slowdown.

However, good luck getting raw 60fps (or even 48) at any respectable resolution.  The 6D is unfortunately limited to ~41MB/s, which is just barely enough to get continuous raw 24fps at full 720p.  You'd be much better off going with 720p60 h264 with bit rate cranked to 3.0x (that's what I did for my footage).
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kyrobb

Remember that if you're shooting 60fps, but slowing down by an additional half speed, you're essentially emulating 120fps. For motion with less blur you'll want a shutter speed of 1/240. Getting enough light indoors can become wicked tricky though.

DigitalVeil

That video was shot with a 1/60 shutter.  Aside from the spots where I had to reduce the Twixtor effect, would you say the motion blur is acceptable?
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Tyronetheterrible

Quote from: DigitalVeil on January 08, 2015, 05:09:09 AM
However, good luck getting raw 60fps (or even 48) at any respectable resolution.  The 6D is unfortunately limited to ~41MB/s, which is just barely enough to get continuous raw 24fps at full 720p.  You'd be much better off going with 720p60 h264 with bit rate cranked to 3.0x (that's what I did for my footage).

Thank you for that information, DigitalVeil, I've been trying to find what the limitations were regarding FPS Override and its respective resolution on the Canon 6D, but could not find anything.

I'm going to experiment with my 6D and see what resolution I can get with Canon 720p-60fps/ML 48fps Override, and then try to upscale it to look at least somewhat decent. I love the look of Raw video too much to let the idea go.

Excellent video, by the way!


Quote from: kyrobb on January 08, 2015, 06:16:16 AM
Remember that if you're shooting 60fps, but slowing down by an additional half speed, you're essentially emulating 120fps. For motion with less blur you'll want a shutter speed of 1/240. Getting enough light indoors can become wicked tricky though.

Thank you, kyrobb, I didn't even take that into account. So you basically determine the ideal shutter speed by adding the fps value you're setting in standard canon menu with the ML fps override value you are setting it to, and then double the sum to get what your shutter speed should be.