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29.97fps and 1/30 shutter

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Bryce Douglass
29.97fps and 1/30 shutter
on Jul 31, 2016 at 9:57:30 pm
Last Edited By Bryce Douglass on Jul 31, 2016 at 10:00:12 pm

I recently made a documentary film. The whole film was shot 29.97 FPS with a 1/30 shutter speed. There was over 200 people (including award winning filmmakers) that saw this film in a small theater. Recently my cousin who's a filmmaker told me I should be shooting 29.97 FPS at 1/60 shutter speed or else my film will look weird.


Why is it that the people that watched my film at 29.97 FPS at 1/30 shutter speed didn't say that it looked weird?

Bryce


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Todd Terry
Re: 29.97fps and 1/30 shutter
on Jul 31, 2016 at 10:09:14 pm

Well "weird" is a subjective description.

If your documentary contained primarily, say, talking heads, or other scenes where there was not a lot of action or movement within the frame, then the unusually slow shutter speed might not have been evident.

Typically, a "normal" frame rate is "one over twice the frame rate." That is, for 24fps shooting you'd typically see 1/48th of a second as "normal," for the 30fps in your case that'd be 1/60th.

Those are the shutter speeds that give the amount of motion blur needed for our brains to interpret the action as smooth and fluid. You don't often see people using a slower than normal speed, but you see people shooting higher than normal all the time. This gives the "narrow shutter" look where motion has a staccato look, often in an attempt to make action scenes look more "actiony." Sometimes it is an effect that is used very well ("Saving Private Ryan") but often it is not (almost every other movie that tries it). Again, it's not too common to see a slower than normal shutter speed as you used. This of course gives the opposite of the narrow shutter look. Rather than giving the sharp blur-free images of high shutter speeds, this is going to introduce much more motion blur in each frame than normal. With scenes with not much movement you might not notice it that much. In scenes with a lot of movement you might notice a sort of "smeary" look to the action since there is twice as much motion blur.

In the future, I'd stick with the "normal" shutter speeds, unless you purposely choose to use one higher or lower for a specific visual effect.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Bryce Douglass
Re: 29.97fps and 1/30 shutter
on Jul 31, 2016 at 10:38:11 pm

Someone else was telling me I should be filming at 24fps. If I did that how would it work for me showing it on television that broadcasts in 30fps?

if my documentary is going to be aired on TV and sold on DVD should I just stick with 30?

what the heck do I do now with a film I'm already making where I filmed one interview at 30fps and 1/30 shutter? can I film the rest at 1/60 shutter and edit in the 1/30 shutter footage or would that screw it up?

Bryce


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Todd Terry
Re: 29.97fps and 1/30 shutter
on Jul 31, 2016 at 11:15:57 pm

It all depends on the look you are going for. 24p is going to give you the most cinematic, filmic look. 60i is going to give you the most instant live "videoy" look. 30fps is going to be somewhere in the middle, although closer to the 24p progressive side than the 30, since it is also progressive.

Yes, you can certainly shoot 24p and distribute on broadcast television or DVD, we do that all the time. I shoot everything at 24p (23.976), yet virtually everything I do winds up on traditional 60i broadcast television. This is accomplished by taking my 24p master and outputting a 60i version just for TV. This all has to do with the "3:2 pulldown"... which is a pretty complex thing to explain, a little above what I can do in a quick forum post. Do a search for that term here or give it a Google and you'll find lots of info about it. It's really all just about the math that is required to convert a second's worth of 24 progressive frames to 60 interlaced fields.

As for DVDs, you can do that the same way, outputting a 60i version of your 24p project for DVD mastering. We don't usually do that, though... in the rare event that we make DVDs (usually just because a client wants one), we just make a 24p DVD, because virtually all DVD players now can handle 24p discs.

I would usually say do not change horses in mid stream, and if you have started a project with certain specs then you should stick to those specs for the entire project. However, sounds like you have only shot one interview at 30fps and 1/30th. In this case, since a talking head is the least likely thing to give away the fact that you've used a slower-then-normal shutter speed, then I think in this case I'd recommend that you bump up to 1/60th for the rest of the footage. They will intercut fine, and if you end up with scenes with more movement or action than a talking head then the 1/60th will look much much more appropriate for that.

What I would not probably do though is switch from 30fps to 24fps. You could, but you'd have to conform or reinterpret your 30fps footage in editing to 24fps, and I couldn't guarantee that you'd be happy with the results. If you want to shoot 24p for the rest of the project, it's probably worth a quick test to see if your 30fps footage looks acceptable inserted into a 24p project. It might, and if it does then you might want to continue the rest of your project at 24p (at 1/48th shutter!) to complete it (assuming that's the look you want), since it's just the one interview at 30fps.

The safest route though would be to continue the project at 30fps (although at 1/60th), and save the more cinematic-looking 24p for your next project.

Hope this helps....

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Bryce Douglass
Re: 29.97fps and 1/30 shutter
on Jul 31, 2016 at 11:21:16 pm

thanks so much.

You have been very helpful. Not just in this post but for my other questions as well I've posted on this forum.

Bryce


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