New frame rates: 12P and 15P

B

Barry_Green

Moderator
I know we've talked about this before, but I just tested it and am pleased to report that it works 100%.

The theory was, can the DVX shoot at frame rates of 12P and 15P?  If you used 24P, with 1/24 shutter, and played the footage back at 200% speed, would it look like 12P?  And for 30P at 1/30th, would that look like 15P?

I used a Tobin Speed Checker, which is a device that lets you precisely calibrate a movie camera's speed.  It has a circle of 10 LED's that flash on/off at crystal-controlled speeds.  If your camera is running at perfect sync speed, five of the LED's will be lit up, and five dark, in each frame.  Any speed variation shows up by the LEDs "walking" in a circle.

It has many speeds, and two of those speeds happened to be 12 and 15 frames per second.

I set the speed checker on 12 frames per second, set the DVX on 24PA, set the shutter speed on 1/24, shot a bit, brought it into Vegas on a 24P timeline, and set the playback rate at 200%.  Sure enough, exactly five LED's lit up, and the pattern held.

I next did the same thing with 30P and shutter of 1/30th, and the speed checker on 15 frames per second.  The same result: exactly half the LED's lit up, half dark, exactly like it would look if you shot film at 15 frames per second.

So, yes, testing verifies it: the DVX shoots at 60i, 30P, 24P, and also 15P and 12P (if you set the shutter appropriately and play back at 200% speed).  It's an even more variable-frame-rate camera than we thought!  And, theoretically, this should give additional frame rates to the DVX100A, with its slow-shutter speeds: you should also get a proper simulation of 2, 3, 4, 6, and 7.5 frames per second as well.  I can't test or verify that because a) I don't have a 100A, and b) the speed checker only goes as slow as 12fps.  But I'm guessing the same technique will work.

(for those technically-minded, no it's not exactly 12P or 15P, it's .1% slower, because the DVX runs at 59.94i, 29.97P and 23.976P for compatibility with NTSC TV sets.  However, for PAL users, you could get 12.5P and it would be an exact 12.5).
 
Re: New frame rates: 12P and 15P

OK, Barry; here's one of your posts worth 10 (at least) of mine.

Questions:

What does this DO for you? I mean, why would you want to? I just shot my sister's wedding in 24p and the shutter speed for much of it was 1/24. If I set the speed to 200%, won't this just look like speeded-up footage? Or is that the point -- smooth footage at twice the speed? If so, I kinda stumbled into it without really thinking about the technical ramifications . . .
 
Re: New frame rates: 12P and 15P

It's just different frame rates that you can use. And yes, it would be "speeded-up" footage, like the Keystone Kops, etc. Or, like in El Mariachi, Rodriguez used slower frame rates for certain segments (like when the hotel guy reached for the phone, that was shot at a slower frame rate for fast motion effects).

It would be much more useful if the DVX had more FAST frame rates, but unfortunately it doesn't. However, it's just nice to know that you have a few more frame rate options available.
 
Re: New frame rates: 12P and 15P

Ah. The word "undercranking" was coming to mind; looks like that's what you were describing. I get it now; we reach! 8)
 
Re: New frame rates: 12P and 15P

You do get 30p as 24p slowmo for 20% when playing back keeping the full vertical resolution. 60i can be double field rendered to create a progessive 60 played back as 24 resulting in a 2.5x slomo.
 
Re: New frame rates: 12P and 15P

Barry

What about the otherway?

What about shooting at a higher framerate and then slowing down in POST? (Like the cool Resovior Dogs or Kill Bill or Beaveheart) OR, would the staccato effect ruin it?

I think I just answered my own question :P

Probally be best shooting with Shutter off (1/48th) and then slowing down in POST, yes?
 
Re: New frame rates: 12P and 15P

The only overcranking you can do is to bring 30P into a 24P timeline and playing it back at 80%, or bringing 60i into a 24P timeline and playing back at 40%. You can't fake other rates by manipulating shutter speed.

I find 60i produces the best slow motion, even though the vertical resolution is softer -- the motion sampling makes up for it. I haven't tried shooting the 60i at 1/120 yet, but that seems like the best way to go -- film at 60fps would have a 1/120 shutter, so it seems like 1/120 would provide the best simulation of 60fps shooting.
 
Re: New frame rates: 12P and 15P

I haven't tried it yet, but couldn't you get 60p by shooting 30p with 1/30 shutter, then change it to 50% (instead of 200%)?
 
Re: New frame rates: 12P and 15P

No, because you didn't capture the frames sixty times a second, you captured them 30 times a second.

In progressive with the DVX, you can't capture faster than 30 times a second.
 
Re: New frame rates: 12P and 15P

Like Barry says this is not quite as usefull as FAST frame speeds would be, but it does have it's uses besides the "Benny Hill" type gag. The fast motion is often used to illustrate hustle and bustle. Like Times square or something like that. Also cloud movement or nature would look cool too. I'm sure there are plenty of other uses. These are kind of a pseudo time lapse. I think "Chungking Express" has some great "not cheesy" uses of slow frame rates....plus plenty of other cinematographic tomfoolery. It's a good movie to check out for clever uses of in-camera tricks.
 
Re: New frame rates: 12P and 15P

[quote author=Zot link=board=news;num=1084556935;start=0#11 date=05/15/04 at 11:39:28] I'm sure there are plenty of other uses.[/quote]

Such as adding a more visceral edge to action sequences and choreographed fight scenes, for instance in the Japanese film 'Versus', undercranking is used to speed up punches and kicks to make them look more brutal. It's useful to have. :)
 
Re: New frame rates: 12P and 15P

What's the benefit of doing this over speeding up regular 1/48th shot footage?
 
Re: New frame rates: 12P and 15P

[quote author=n0signal link=board=news;num=1084556935;start=0#12 date=05/17/04 at 16:47:49]

Such as adding a more visceral edge to action sequences and choreographed fight scenes, for instance in the Japanese film 'Versus', undercranking is used to speed up punches and kicks to make them look more brutal. It's useful to have. :)
[/quote]

Witness 7 seasons of "Highlander" . . .
 
Re: New frame rates: 12P and 15P

Speeding up footage shot at 24p with a 1/48th shutter results in a look akin to scanning a video tape in fast forward; you're getting the same amount of visual information at a faster rate.

Shooting less frames per second results in less temporal information, and will look more like footage from an undercranked movie camera, rather than the comparatively (though subjectively) less natural-looking sped up 24p footage; watch early episodes of "Star Trek: The Next Generation" and "The X-Files" for examples of this, where they simply sped-up in post footage that had been shot at 24p and telecined to 60i.

Compare that to film footage shot at lower frame rates, a technique used both to punch up action sequences (among many others, "Mad Max" and "The Road Warrior" frequently utilized the technique in the car and truck chases), to shoot time-lapse footage, and for comic effect ("A Hard Day's Night," the aforementioned "Benny Hill").
 
Re: New frame rates: 12P and 15P

[quote author=Chris link=board=news;num=1084556935;start=0#13 date=05/18/04 at 19:26:35]What's the benefit of doing this over speeding up regular 1/48th shot footage?[/quote]

The benefit is that you're getting an exact frame-for-frame frame-accurate 12P or 15P video. Speeding up otherwise-shot footage may make the footage last the same amount of time, but it's not the same as what you'd have gotten if you'd actually shot at those frame rates.

Same basic idea as "why shoot 24P when you could just use DVFilm Maker software to convert 60i to 24P?" Because converted images may approximate it, but they're not the real deal. The 12P and 15P techniques give you the exact same results (motion-wise, etc) as if you'd shot on a film camera running at 12 or 15 fps.
 
barry - is this the same for pal (25p) dvx100a? and could give info on how to achieve the extra frame rates with the dvx100a (if it is also applicable to the pal models)

thanks
 
With PAL the only additional frame rate (using this technique) would be 12.5fps, and would be accomplished by shooting 25p at a 1/25 shutter speed, and then playing back at 200% speed in post.

Also, by using the slow shutter speeds you could create 6.25fps, by shooting 25p at 1/12, and also 3.125fps, by shooting 25p at 1/6.
 
dang - y couldnt pal users get two speed options too :) -was hoping to use 15fps... thx though barry - curiously - did the dvx100 not have the slower shutter speed? looking forward to experimenting with 6.25 and 3.125 experiments...

btw are these the kind of things in your dvd/book?
 
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