24p or 30p

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joechiazza

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24p or 30p

PostWed Apr 02, 2014 7:54 am

Just curious. Is there any reason to shoot at 30p and then downscale to 24p in post? I was reading somewhere that shooting at higher frame-rate is more cost effective at getting a sharper image than shooting at 4k. Especially considering disk space.

Anyone have any thoughts?


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Dustin Boswell

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Re: 24p or 30p

PostWed Apr 02, 2014 8:12 am

I don't believe it has anything to do with image sharpness so to speak (I know that for "Slow Motion" shots it results in a smoother shot), but more about Motion Blur. I'd say the best thing to do is to shoot to the standard at which you will be delivering the finished product (24p for Movies, 30p for NTSC T.V., 25P for PAL).

I'd think that shooting at a higher framerate would actually increase the amount of storage needed, as you are adding +25% FPS (which, if shooting DNG RAW would mean 25% more images on your hard drive I'd think).
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Christian Horne

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Re: 24p or 30p

PostWed Apr 02, 2014 8:19 am

I only shoot at 30p when I'm shooting to make Stockfootage as this frame rate seems the norm for that, I don't think it technically makes the image sharper but it may be perceptual because you will get less flicker in fast motion and you should be shooting at a faster shutter speed (1/60). Shooting at 24p has more advantages and is a more flexible frame rate to use i.e. storage, BluRay spec, film out spec rotoscoping can be sped up to 25p for PAL land etc. Maybe do some comparison testing yourself and sit as far back from the monitor as you would in a normal TV viewing situation and see what you think :)
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Howard L Hughes

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Re: 24p or 30p

PostWed Apr 02, 2014 2:47 pm

i shoot at 30fps because i prefer it over 24fps.
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bhook

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Re: 24p or 30p

PostWed Apr 02, 2014 2:50 pm

I shoot nearly everything at 29.97.
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Anthony Lefty

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Re: 24p or 30p

PostWed Apr 02, 2014 3:23 pm

Anytime I am shooting for short films or features I shoot in 23.97. If I am shooting documentary or sports, I shoot 29.97
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joechiazza

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Re: 24p or 30p

PostWed Apr 02, 2014 3:27 pm

So the question is: is there any advantage to shooting at 30p or 29.97 and then rendering in a 24p timeline (not slow motion). Specifically for film work not documentary.
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Giles Sherwood

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Re: 24p or 30p

PostWed Apr 02, 2014 3:33 pm

You definitely don't want to convert 30p to 24p unless you're just reinterpreting the frame rate in Cinema Tools or After Effects. 23.98p can fit into 29.97i, but not the other way around. You'll end up with dropped frames and jerky motion if you try to "downsample" the frame rate like that.

If you were shooting HFS at 48p on a RED or something, you could convert to 24p, which is apparently what Peter Jackson did for the 24fps versions of the Hobbit films, and he says he prefers the way motion is rendered using that method.
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David Hessel

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Re: 24p or 30p

PostWed Apr 02, 2014 3:41 pm

joechiazza wrote:So the question is: is there any advantage to shooting at 30p or 29.97 and then rendering in a 24p timeline (not slow motion). Specifically for film work not documentary.


No, the only reason that shooting 30P makes images sharper is the faster shutter speed, hence less motion blur. 24P @ 180 degrees = 1/48 seconds, 30P @ 180 degrees = 1/60 seconds. If you want 24P but the same sharpness it would be the same as using a 144 degree shutter angle.

Also there is no way to perfectly convert 30P to 24P, going from 30P to 15P is easy just keep every other frame but going to 24P to really do it %100 correct you would need frames in between the frames that were recorded so the conversion is always an approximation.

Save yourself some trouble and hard drive space and just shoot with a smaller shutter angle if you want a sharper image.
Last edited by David Hessel on Wed Apr 02, 2014 4:53 pm, edited 1 time in total.
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joechiazza

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Re: 24p or 30p

PostWed Apr 02, 2014 3:50 pm

dhessel wrote:
joechiazza wrote:So the question is: is there any advantage to shooting at 30p or 29.97 and then rendering in a 24p timeline (not slow motion). Specifically for film work not documentary.


No, the only reason that shooting 30P makes images sharper is the faster shutter speed, hence less motion blur. 24P @ 180 degrees = 1/48 seconds, 30P @ 180 degrees = 1/60 seconds. If you want 24P but the same sharpness it would be the same as using a 144 degree shutter angle.

Also there is no way to perfectly convert 30P to 24P, going from 30P to 15P is easy just keep every other frame but going to 24P to really do it %100 correct you would need frames in between the frames that were recorded so the conversion is always an approximation.

Save yourself some trouble and hard drive space and just shoot with a smaller shutter angle if you want less motion blur.


Great answer. Thank you!
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Mac Jaeger

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Re: 24p or 30p

PostWed Apr 02, 2014 4:28 pm

Shooting in 24p or 30p? Depends on what you are going to do with your material later. If you shoot for cinema / bluray, shoot 24p. If you aim at TV, shoot 30p (or rather 29,xx). Framerate conversion is nasty, you should avoid it whenever possible.

30p does not provide any advantage over 24p regarding image sharpness, as long as you choose the same shutter speed (not angle!). Of course 30p will have less motion blur than 24p if you shoot both at 180° - but if you are worried about motion blur, you can always lower the shutter angle (24p at 144° is exactly the same shutter speed as 30p at 180°, namely 1/60 second expositions, resulting in the exact same amount of motion blur). 30p will result in more fluid movements than 24p, but only if you present the footage at 30p later (and then you should shoot 30p anyway) - if you downconvert 30p footage to 24p in post, you will even get worse stutter in movements (additional micro stutter due to pull down) than you'd see in native 24p footage.

The question should not be whether you should shoot at 24 or 30 frames per second, but whether you should produce/deliver/view in 24 or 30 or even 48 frames per second.
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Denny Smith

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Re: 24p or 30p

PostWed Apr 02, 2014 4:58 pm

NTSC is 29.97 frame rate at 59.xx shutter speed for TV delivery in US, including cable feeds.
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Vince Gaffney

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Re: 24p or 30p

PostWed Apr 02, 2014 5:11 pm

I shoot in 23.97p and I deliver SD masters at 29.97i and HD masters at 23.9p. Extreme Reach Media bought the disaster that was DG systems and they now accept ProRes LT masters as well. So there's that.
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Christian Horne

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Re: 24p or 30p

PostWed Apr 02, 2014 5:55 pm

Don't forget that over 2 thirds of the world is PAL system, if you shoot in 24p the conversion up to 30p or 29.97 isn't so bad as the NTSC world has been used to watching that on there screens since TV was born. There is no universal frame rate, on consumer camera's here in the UK there isn't normally a 24p option, my Panasonic shoots 25p 50i or 50p because of fixed shutter speeds, I have to convert to 24p for Bluray. It's all about planning ahead and testing various ways to do frame rate conversions and then see how you like the results :)
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ChrisBarcellos

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Re: 24p or 30p

PostWed Apr 02, 2014 6:30 pm

I have always understood:

1. That 30p does not convert well to 24p because of the necessary interpolation of frames.

2. That if you want to shoot at a higher rate, then shoot 60i (which is probably what is meant by 29.97i) and that will actually convert more easily because of structure of 60i half frames.

3. The reason most narrative film shooters choose 24p is because of the temporal more filmic feel of 24p. That means that they think it looks more like film to the viewer.

4. In addition, if the film was to transfer to a film medium for distribution for projection, 24p is what the film will be transferred to.

That begs the question: With the advent of digital projectors, does it matter anymore what frame rate a director chooses in terms of projection at theaters ?
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Christian Horne

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Re: 24p or 30p

PostWed Apr 02, 2014 7:30 pm

The answer is yes, film is what it is because less more, lesser frame rate less saturation, less sharpening, the 'Hobbit' will testify to this notion and true cine maniacs turn off their 100hrtz option on the TV sets :)
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Mac Jaeger

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Re: 24p or 30p

PostWed Apr 02, 2014 10:36 pm

And as long as DVD/BluRay and TV-Sets are not flexible enough to present all rates from 23.97 up to 60p i will stick to shooting 24p or 25p for most of my work, depending on the clients wish to publish on BluRay or PAL-DVD.
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Alex Klutchevski

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Re: 24p or 30p

PostWed Apr 02, 2014 11:34 pm

Compressor from FCP Studio can give you a really good result converting any frame rates to any one. It is using flow motion for that, But sometimes there can appear some motion glitches because off conversion, but on such not big differences on frame rates it isn't noticeable.

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