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real movie 24fps vs. video 24fps

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Ryan Santos
real movie 24fps vs. video 24fps
on Mar 10, 2009 at 2:25:06 am

Whenever I look at video clips shot at 24fps, they're not smooth. But when I watch real hollywood movies either in cinemas or in DVD, they look smoother than a 24fps video. I understand that movies are also shot at the rate of 24fps. Why is this so? God bless.


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Rick Wise
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 3:05:18 am

You have put your finger on one of the conundrums facing us all. You are delving into mixed media. Film shot at 24 fps is usually viewed in 48 glimpses/second. That is, the usual shutter on a film projector is a butterfly shape, so that each frame is flashed on the screen twice (sometimes split in 1/3rds so each frame is flashed 3 times.) Our eyes have become accustomed to reading this screen as smooth, continuous action. What you are seeing on a DVD is actually 60i: each film frame is duplicated into two fields, and for some of the time, each frame is also duplicated to four fields so that the total per second is 30 frames or 60 fields.

24p video is seen at 24 times/second. Less information from frame to frame.

There are some of heretics, including me, who find that shooting video 30p is more like 24-frame film than 24p video as far as apparent motion goes.

There are many more hoops video shooters have to jump through to achieve a "film" look. Frame rate is only one.

Rick Wise
director of photography
and custom lighting design
Oakland, CA
http://www.RickWiseDP.com
http://www.recessionvideo.net
http://www.linkedin.com/in/rwise
email: Rick@RickWiseDP.com


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Todd Terry
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 3:07:24 am

Some guys might chime in with some technical/electronic explanations, but I will take a stab at the aesthetic explanation...

Watch a good 60i monitor sometime and compare (properly) telecined film with 24p video. Step though frame by frame, and you'll see they are technically exactly the same... 3:2. That is, you'll see three progressive frames followed by two interlaced frames, which then repeats indefinitely.

So... technically they are much the same. So why do they often look different?

Film has been shot at 24fps for darn near 100 years. It is "stuttery." Just as much as 24p video. One of the chief differences is, cinematographers used to shooting 24fps know exactly how to do it. Some care must be taken to do it right. Fast pans, the wrong kind of action crossing the frame at the wrong rate, etc., will yield just as must stutter as video. Practiced cinematographers know how to avoid this. Pans, for example, ideally shouldn't exceed a specified rate. Charts in the ACS manual will tell you "do not exceed" pan rates (expressed in degrees per second) for specific focal lengths, etc. Old schoolers rarely actually refer to these charts... do it enough and you can do it by eyeball.

A lot of 24p video, though, is shot by those who are used to shooting for video (and may have never even shot real film), and therefore shoot 24p video the same way they've been shooting 60i video for years and years. That often yields very poor results, especially in scenes with a lot of motion. 60i is very forgiving of motion artifacts like that... 24p is definitely not. You must shoot 24p correctly or the motion flaws will show.

Secondly 24p video is usually shot with 2/3", 1/3", or in some cases 1/2" chip cameras (with the exception of "big chip" video cameras such as the Panavision Genesis, RED ONE, or cameras using a DoF converter). This "target image size" is much much smaller than a film frame, ergo the depth-of-field is much deeper. Sharp foregrounds and backgrounds are much less forgiving than even ever-so-slightly soft ones, and the "stutter" or "judder" seems much more pronounced.

Shoot 24p exactly as if you were shooting film, and the stutter and judder won't be any more pronounced than if you are shooting real celluloid. It can look very good, indeed.


T2

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






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Chris Blair
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 4:03:37 am

Great explanation Todd! I will add that many camera manufacturers have gone to great pains to create scene files that configure camera settings to greatly minimize the stutter you might be seeing.

Panasonic's presets are great examples. Set the camera to the 60i defaults, then JUST turn on the 24P mode, and the footage is barely watchable. Load one of Panasonics presets designed for 24P shooting, and voila, almost all stutter is eliminated, except of course if you violate the rules Todd just detailed.

But as the first reply noted, shooting 30p is a nice compromise, and some cinematographers will shoot film content that is only intended for video (like TV commercials) at 30fps to avoid having to add pulldown in telecine. Of course, that can add significant cost to film stock, processing and transfer if you're shooting an hour-long drama, so that's why it's not often done on those.

But these days, film is used less and less for even dramtic television programs.

Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com


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Todd Terry
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 4:26:47 am

Yeah, Chris is right... through the years lots of filmed television programs were shot at 30fps.

I shoot almost nothing but TV commercials, and have done both. Frankly I couldn't tell much difference in spots I shot in either 24fps or 30fps in both 16mm and 35mm.

And yes, film is falling out of favor just a little bit for primetime dramatic series, as more and more are going HD (although the big-budget dramas are still predominently 35mm). Actually S16mm is doing well for primetime these days. Check out the HD network feeds on a good large display of S16mm shows ("My Name is Earl," "Scrubs," and the COW's own Todd McMullen's "Friday Night Lights" just to name a few). The quality is phenominal.


T2

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






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Ryan Santos
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 4:42:04 am

Thanks Chris and Todd. But what Panasonic are you talking about (that can remove the stutter by just adjusting the presets)? Can the HPX150 do that? How about the HVX200? I know they're not BIG cameras but those are the only ones available here.


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Rick Wise
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 5:37:46 pm

When we shoot table-top with film, we shoot at 30 fps to avoid that 2/3 pull-down. On very tight, table-top close-up moves, 24-frame pull-down can kill the move. At times, when shooting a pan across a label, we'll shoot 60 fps. In telecine transfer, that becomes one frame of film for each field. Really helps (and also chews up film fast.)

Rick Wise
director of photography
and custom lighting design
Oakland, CA
http://www.RickWiseDP.com
http://www.recessionvideo.net
http://www.linkedin.com/in/rwise
email: Rick@RickWiseDP.com


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john sharaf
Re: real movie 24fps vs. video 24fps
on Mar 10, 2009 at 7:07:27 pm

Ryan,

I'm at a loss myself to think of any presets (other than 180 degree shutter) that would affect the film like motion from a video camera. Of course there are gamma, detail, knee, matrix and other settings (presets) that make video more filmic or filmlike, in addition to the biggy being 24fps in progressive mode with half shutter (180 degrees aka 1/48th of a second).

JS





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Chris Blair
Re: real movie 24fps vs. video 24fps
on Mar 12, 2009 at 12:09:54 am

john sharaf
I'm at a loss myself to think of any presets (other than 180 degree shutter) that would affect the film like motion from a video camera. Of course there are gamma, detail, knee, matrix and other settings (presets) that make video more filmic or filmlike, in addition to the biggy being 24fps in progressive mode with half shutter (180 degrees aka 1/48th of a second).

John,

I would've agreed with you 100% until we started using Panasonic 2/3" cameras with the CineGamma technology. We were initially extremely disappointed with the SDX-900 we bought back in 2004 because by just switching to the 24P mode and adjusting the shutter settings to their recommendations resulted in footage that was literally impossible to watch it was so jerky.

We called them and they (along with many other users on the Cinematography.com forums) urged us to just load the free scene files that Panasonic had on their website. Like you, I thought, "how could these make a difference in the motion?" But I relented, downloaded them and then transferred them to the SD card of the camera, then loaded one and tested it at 24P. I was amazed. It looked totally different. Just to compare...I reset the camera to it's factory defaults, then just turned on 24P and adjusted the electronic shutter to what the manual instructed for 24P shooting (it approximated 1/48th of a second)...and motion returned to looking like dog crap. I tried the shutter at it's default and played around with a dozen other settings. Still looked like crap.

I then re-loaded the scene file from the SD card...and AGAIN...it looked great!

I can't explain it...and I don't have the time or inclination to figure it out, but there's something about the combination of settings in their scene files that produces smoother motion when using 24P.

If I'm not mistaken...I believe those scene files will work across all their lines of cinema style video cameras, including the DVX and HVX line.




Chris Blair
Magnetic Image, Inc.
Evansville, IN
http://www.videomi.com


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john garrad
Re: real movie 24fps vs. video 24fps
on Oct 17, 2010 at 3:14:55 pm

I would like someone to explain why even Blue Ray full Hi-def movies labeled as 1920 x 1080 pixels do not look as clear as live full hi-def TV one sees on their cable channel. The difference in resolution can clearly be seen on my 50-inch Panasonic plasma 1920 x 1080 display. I'm sure that it is the video TV camera which shoots at a higher frame rate per second, e.g., 30 fps vs. 24 fps. All of the technical information in this discussion does not seem to answer this question. Thanks.


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John Sprung
Re: real movie 24fps vs. video 24fps
on Mar 11, 2009 at 1:11:43 am

There are two issues here that affect smoothness of motion: 3-2 pulldown, and shutter angle.

Given that you see the same smoothness both in film theaters and from DVD, we can eliminate a sensitivity to 3-2. People who grew up in the PAL/SECAM countries tend to be the ones who are bothered by 3-2. We from the NTSC world get used to it. 3-2 gives 50% more time to every other frame, resulting in a 12 cycle per second vibration added to the motion.

Shutter angle determines how much motion blur there is. Film cameras are traditionally used with angles near 180 degrees, not because that's the best choice, but rather because it takes about half the frame period to mechanically pull down the film and register it accurately. Using significantly smaller angles results in sharper frames, because there's much less motion blur. Objects don't move as far in the brief time that the shutter is open. But that's counterproductive to the illusion of motion. It gives you a really fast slide show instead of movies. The smaller the shutter angle, the slower the point at which moving objects break the illusion and start to skip.

It sounds like you've been seeing video shot with small shutter angles. With digital cameras, we now have the opportunity to go the other way, to angles much larger than 180, even to within a hair of a full 360. Surprise, the wagon wheels blur out instead of going backwards if you shoot with a 359 degree shutter.



-- J.S.




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Chris Wright
Re: real movie 24fps vs. video 24fps
on Mar 11, 2009 at 3:22:51 am

I'm going to take a stab at this smoothness thing. First off, I have noticed that the distance an object travels per frame is consistant on film and not so on DV. That creates more jerkyness than any blur can cover up.

That may be why DV pulldown cameras like the dvx100a still do not look like film. The spacing between movement is not consistant. Besides that, their pulldown is wrong.

True reverse pulldown should follow the pattern WWSSW, but most camcorders do not do that pattern. That's why RED works so well, its taking 24 pictures not frame percentages with messed up cadences.

Ironically, even with a $10,000 Hi Def Tv, you're still only seeing 23.9 fps.





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