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Shutter angle preference shooting 60fps knowing post will speed ramp to realtime

camera shutter angle shutter speed slo motion

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#1 Andrew Russo

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Posted 02 September 2015 - 03:15 PM

Does anyone have experience shooting slo-mo that the editor will then speed up to real time in post? What shutter angle makes the most sense for best results of motion blur on both ends? Most likely shooting at 60 fps.

 

Thanks.


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#2 David Mullen ASC

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Posted 02 September 2015 - 03:46 PM

Traditionally you'd employ a 180 degree shutter, which will make your slow motion look better but your conversion to 24 fps look a bit choppier as if shot with a shorter shutter angle. But that is preferable to shooting the slow motion with a long shutter time to make it look normal at 24 fps but smeary in slow-motion.

 

For example, if you shot 48 fps with a 180 degree shutter, the 2X speed up to look normal would make it look like 24 fps shot with a 90 degree shutter angle (because the per frame exposure was 1/96th instead of 1/48th).

 

Of course, today, there is software to add more motion blur into the footage so that 90 degree look can be softened.

 

Another option is to find some halfway shutter angle like 240 degrees or 270 degrees, get a little more blur in the slow-motion but a little less choppiness in the normal speed version.


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#3 Andrew Russo

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Posted 02 September 2015 - 09:58 PM

That was my feeling as well especially since there won't be too much fast movements or actions to feel the staccato choppiness.  

 

Thanks again David!


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#4 cole t parzenn

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Posted 03 September 2015 - 12:16 PM

Are you able to shoot at 72 fps? You should be able to fake 24/180 by shooting 72/180, interpolating the "missing" frames, and blending a real-interpolated-real frame sandwich, then skipping the next three frames (interpolated-real-interpolated). In theory.


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#5 Steven Wyatt

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Posted 03 September 2015 - 01:10 PM

Hello!

 

I just wanted to add a further question to this post regarding speed ramping, how would one achieve a speed ramp in camera?

 

I've linked in this showreel as an example for reference (watch at 48 seconds in, where the foot hits the puddle) :

 

 

Would this be an in-camera effect or a post production one?

 

Thanks

Steve


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#6 David Mullen ASC

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Posted 03 September 2015 - 01:13 PM

Odds are high that the ramp was done in post, just because it can be hard to trigger the ramp in-camera at precisely the right moment with some types of actions.  Anyway, to answer your question, you'd need to use a camera that can speed-ramp if you want to do it in-camera and decide if you want to compensate for the exposure change by doing an f-stop change or a shutter angle change.


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#7 Jeff L'Heureux

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Posted 03 September 2015 - 04:10 PM

Hello!

 

I just wanted to add a further question to this post regarding speed ramping, how would one achieve a speed ramp in camera?

 

I've linked in this showreel as an example for reference (watch at 48 seconds in, where the foot hits the puddle) :

 

 

Would this be an in-camera effect or a post production one?

 

Thanks

Steve

I think David's right and this ramp was done in post.  The entire shot was likely done in slow motion and in post they sped up the portion pre-ramp.  In cases where they really want to fool the viewer they can even add back in motion blur.  Zack Snyder does this a lot in his action scenes in movies like 300.

 

I actually shot a real ramp shot on 16mm on my most recent film from 24fps to 75fps and needed to compensate for the exposure change mid shot.  I smoothed out the rest in the color grading.


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#8 Dan Barham

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Posted 03 September 2015 - 11:28 PM

Hello – we definitely did it in post. All the slowmo in our reel was shot at frame rates like 120 & 240 at 180 degree shutters, then ramped in post. For motion blur we used RSMB.

 

Hope that helps!


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#9 Tom Yanowitz

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Posted 14 March 2016 - 06:30 PM

Would you say the highest in our framerate, the more we can froget about the 180° rule ?

 

I always thought what we call the 180° was more in fact the "amount of blur at or near 1/50th of a second", so a rule specific to real time shots.

 

 

If we suppose that the subject isn't something super fast, do we agree that 360°, if available, is the best choice to save a stop of light or of lens ?

 

Even at 50 or 60fps I'd be curious to know at what "subject speed" point 360° would become to blurry to the eye (if anybody's done some test on this)


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#10 Satsuki Murashige

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Posted 14 March 2016 - 10:19 PM

The '180 degree rule' is an entirely different thing that has to do with camera placement when shooting coverage. You probably already know this but it is best not to mix up these terms.

The shutter speed that is appropriate for a particular shot is very subjective, depending on both the subject matter and personal taste. When I use higher frame rates, I often want to close down the shutter so the individual frames are sharper. Since each frame is on screen for a longer period of time, any motion blur will be more obvious. One Phantom Tech that I know recommends a 90 degree shutter in many cases. Of course, sometimes you simply don't have enough light to do it.
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#11 Tom Yanowitz

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Posted 15 March 2016 - 10:59 AM

Yeah I don't know why I called it "the" 180° rule.

 

Is each frame really viewed longer though ?

I'm not sure how digital "shutters" work for TVs and theaters, but what ever the time (what is it by the way) a frame is on the screen, it'll be the same for real time shots and slow motion isn't it.

 

And the fact that we find blur pleasing for real time footage does not apply for slow motion ?

 

(these are actual questions, not rhetorical ^^)


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#12 Satsuki Murashige

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Posted 15 March 2016 - 04:20 PM

Each frame of footage on a slow motion shot isn't on screen longer. However, each shot is typically held longer by the editor so that you can watch the slow motion play out.

Think of a typical high speed insert shot like a glass of water falling to the ground and breaking, a shampoo commercial where the girl flips her hair, or an action shot in '300' where the hero is slicing the enemy with a sword. Your eye has time to scan the entire frame, to luxuriate in the details of movement. Motion blur is a lot more obvious on shots like this. Where the eye can appreciate detail, you add it in. Where that extra detail would be distracting, you remove it to direct the eye where it needs to go. Just like with framing, lensing, lighting, and grading.
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