Shutter speed for slow motion if unsure of final playback fps - especially post ramps

M

Marshallarts

Well-known member
This question has been bugging me and I haven't been able to properly test this out, I was hoping someone here has.

If I have a shot that I think would look good in slow motion (60fps for example) but do not know if post will, (1) use it in slow motion, (2) use a speed ramp on it in post, or (3) decide they prefer the normal 24fps look, how should I approach shutter speed?

If I know 100% it will be used in slow motion I would use a 180 degree shutter, but if there is a possibility they may want to speed it up to normal speed, or ramp it in post I am afraid that shutter will be too fast for the 24fps portions.

Does no shutter in slow motion look particularly bad? But will it save the footage in case post wants to speed it up to normal speed? Has anyone experimented with the compromise here?
 
You should avoid the problem by coordinating all of this with post before you shoot. This is a "fix it in pre" question.
 
Yeah, I'd definitely try your best to figure out the end goal before hand.

If not, you could shoot it with a 180 degree shutter at 24fps and then again at 180 degree shutter at 60fps (assuming it will be possible to shoot more than once.)

I have shot 60fps at 1/60th shutter before, used some of the footage for slow motion, and some of it was dropped into a 24fps timeline. It worked pretty well, but it would have looked better if I could have known ahead of time what shots were going to be slowed down and which ones weren't.
 
I think what he's asking is what shutter speed would you use for one specific shot when you know it will be slowed down in post, since either the real time parts of the shot or the slowed down part will not be recorded the optimal amount of motion blur.

I would set the shutter speed so that the slowed down part of the clip has the correct amount of motion blur. It's been a while since I've done anything of this nature but I'd have to guess that adding more blur in post is much easier than taking it out.
 
Moseph said:
I think what he's asking is what shutter speed would you use for one specific shot when you know it will be slowed down in post, since either the real time parts of the shot or the slowed down part will not be recorded the optimal amount of motion blur.

I would set the shutter speed so that the slowed down part of the clip has the correct amount of motion blur. It's been a while since I've done anything of this nature but I'd have to guess that adding more blur in post is much easier than taking it out.
Click to expand...

Thanks for rescuing me, yes you know what I'm asking. And I would think your method would be the right way to go about it.
 
For me the biggest problem wouldn't be shutter speed, but actual fps. If you can shoot 48p or 72p, with shutter set at 1/60s or 1/100s or something like that that doesn't give you light flicker, you can use it as 24p and motion blur will be a bit too crisp but not too much. Not easy to spot if you don't tell your audience to look for it (1/200s would be more obvious). Now, if you shoot 60p and put that into a 24p timeline, even if 2.5x seems like an easy divide, the video can look awful if you don't use the right processing to get your blended frames. And if the camera moves around a lot, it can look horrible no matter what you do.

I know because I made that mistake just this past weekend.

A few months back I shot this Batman vs Bane fight, at 60p-1/100s, then edited on a 24p timeline with all kinds of frame rate conversions:

Since that one was looking fine, this weekend I decided to shoot another cosplay fest fully at 60p-1/100s, so I would be able to choose in post what was going to be slow motion and what not. Huge mistake. I was using a flycam to get a very dynamic look. Nobody has complained yet, but I know it looks like crap. A real pity, since content is so awesome.
 
distilled down: using a 180 degree shutter, which would be to use double what your frame rate is, is usually the best starting point.

if you really don't quite know what you'll be doing in editing, then at the very least do some testing, have at it at 60P, and start with 1/100, and go up until you see significant staccato effect (jitttery, action movie like motion), then dial it back to where you like the amount of motion blur. then take those shots and see if you can edit them as you like.
 
Thanks for the additional replies. And thanks Samuel H for taking the time to provide those examples, why did it work the first time but not the second? I know you've probably tried everything but if it worked before perhaps there was a conversion issue? And just to ease your concern, I know it's your baby and you're upset with the look, but it's really not that bad. :)
 
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