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Difficulties in shooting HFR digital


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#1 Philip Mayor

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Posted 12 December 2012 - 04:12 AM

I am wondering if anyone here has specific knowledge about the difficulties one is faced with in shooting HFR.

For example, does a set require more light?

Does HFR wash out color? Apparently on Hobbit they had to add extra saturation to sets, even makeup to compensate for this.

Are professional camera moves harder to achieve? Is camera operating more difficult?


Those are some thoughts I have that I'm trying to answer but maybe others have other ones. We've already heard that increased detail means imperfections in the sets are more noticeable, so I'm already aware of that problem.

Much thanks and I'll check back regularly.
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#2 Oliver Hadlow Martin

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Posted 12 December 2012 - 04:25 AM

More difficult to hide imperfections in camera movements. Pulling focus in 48fps would need to be more precise potentially; less room to hide focus pulls considering there is less blur, making them easier to see?

And yes depending on settings they used on camera, shutter angle, shutter speed etc, you could need more light.

Edited by Olliehm, 12 December 2012 - 04:27 AM.

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#3 Mike Lary

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Posted 13 December 2012 - 03:33 AM

Does HFR wash out color? Apparently on Hobbit they had to add extra saturation to sets, even makeup to compensate for this.


You're probably thinking of compensation they made for the color shift introduced by the mirrors on their 3D rigs. That had nothing to do with HFR.

HFR has less blur, and that means more detail. More attention needs to be paid to makeup and set design. Think of when high resolution digital cameras came on the scene and started seeing through thin washes of paint on set walls and exposing flaws in actor's skin. HFR will kick that up a notch.
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#4 Philip Mayor

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Posted 13 December 2012 - 03:46 AM

Why would color correction be needed for 3D? I've never heard this before.
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#5 Philip Mayor

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Posted 13 December 2012 - 03:51 AM

...depending on settings they used on camera, shutter angle, shutter speed etc, you could need more light.


That's just as true for 24fps. I asked what difficulties unique to HFR.
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#6 Oliver Hadlow Martin

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Posted 13 December 2012 - 04:08 AM

Well you need more light than 24 in a standard configuration, so I guess it is more unique. And especially if they start ramping it up to 60 and above fps.

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#7 Guillaume Cottin

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Posted 13 December 2012 - 01:35 PM

Hi everyone,

HFR or high framerate can be beautiful and lifelike, but is also very demanding indeed. The smallest bump on the dolly tracks reveals the existence of the camera. Handheld footage, although very fluid (the safe panning speeds are doubled) is unforgiving. On the Hobbit, Andrew Lesnie has resorted to Technocrane for most shots.

When shooting HFR, the sharpness of the diminished motion blur is compensated by using a more open shutter. "The Hobbit" used a 270-degree shutter as "standard" (as opposed as to the usual 180 degree). Combined with the framerate of 48 fps, this equals to a shutter speed of 1/60th of a second. Which is not very different from the traditional 1/48 shutter speed -and therefore movment rendition- we are used to. It still remains twice as fluid as standard footage.

We have the habit to associate 24fps footage with cinema, and more fluid footage with documentary or TV. Over a century ago, 24 fps was conceived as the smallest speed to allow sync sound. This norm emerged from a technical compromise : it does not correspond to the way we see the world. But eventually, we all got so used to it that it ended up being a signature of cinema, helping to put the viewer in a "suspension of disbelief" state, and I think this is why many people who watched "The Hobbit" reported the feeling that they were looking at a documentary and not a film. The more films will be shot and released in HFR, the more this cultural obstacle will be overcome.

The case of The Hobbit (since it is the only feature film widely released in HFR so far) is a bit special also, because not only was it shot in HFR, but it also is very heavy in special effects! I found that some special effects felt fake : shot by shot, and sometimes within the same shot, I could tell with certitude what was filmed on set and what was created with CG.
I think that it is due to a very slight difference in motion rendering between computers and cameras, even if both are set to the same framerate. I would love to investigate that issue.
Apart from that, I believe that Peter Jackson and his team experienced big schedule issues and had to release a film that was... well, unfinished -on the special effects side -but not only.
Courage, Peter! You still have two more films!

G.C.
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#8 Philip Mayor

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Posted 13 December 2012 - 09:58 PM

I found this interesting:

"Lets think about this: a 270 degree shutter angle at 48p fps is the same as a 1/64 second shutter speed per frame. However when you remove every other frame to come up with 24p fps the shutter speed is still 1/64th of a second. Each frame will always stay at the speed you shot it. The motion blur you captured per frame is the motion blur you are stuck with and there is little you can do about it. So 24p fps at 1/64th of a second shutter speed means that the shutter is now only letting in light for 38% of the total time the camera is filming. It’s the same look you would get if you shot with a 136 degree shutter angle at 24p fps. This means that the look of the film is now more jerky than it would have been if it had just been shot using the normal 180 degree shutter rule. Its shutter speed is not 2x the frame rate where it would have looked natural, it is now higher.

So what does this all mean? Jackson explained the shutter angle, “… shooting at 48 fps with a 270 degree shutter angle. This gives the 48 fps a lovely silky look, and creates a very pleasing look at 24 fps as well. In fact, our DP, Andrew Lesnie, and I prefer the look of 24 fps when it comes from a 48 fps master.”

This is kind of a double talk in that what he is saying here is that he likes a super smooth 48p fps look but when it comes to 24p fps he prefers a slightly more stuttery look than the norm. My opinion is that he is simply compromising between a high frame rate for 3D and a normal looking shutter speed for 24p. If he was shooting for 3D ONLY he would likely shoot 60P 1/120 second shutter. That could never be converted to a normal looking 24p though. If he was shooting for NON 3D only he would shoot at 24p 1/48th of a second, the industry standard. I believe that is because we are in a transition from old to new technology and he is shooting with both in mind; it’s a compromise."

http://www.videocand...pany.com/?p=224
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#9 Marcus Joseph

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Posted 14 December 2012 - 05:09 AM

I found this interesting:

"Lets think about this: a 270 degree shutter angle at 48p fps is the same as a 1/64 second shutter speed per frame. However when you remove every other frame to come up with 24p fps the shutter speed is still 1/64th of a second. Each frame will always stay at the speed you shot it. The motion blur you captured per frame is the motion blur you are stuck with and there is little you can do about it. So 24p fps at 1/64th of a second shutter speed means that the shutter is now only letting in light for 38% of the total time the camera is filming. It’s the same look you would get if you shot with a 136 degree shutter angle at 24p fps. This means that the look of the film is now more jerky than it would have been if it had just been shot using the normal 180 degree shutter rule. Its shutter speed is not 2x the frame rate where it would have looked natural, it is now higher.

So what does this all mean? Jackson explained the shutter angle, “… shooting at 48 fps with a 270 degree shutter angle. This gives the 48 fps a lovely silky look, and creates a very pleasing look at 24 fps as well. In fact, our DP, Andrew Lesnie, and I prefer the look of 24 fps when it comes from a 48 fps master.”

This is kind of a double talk in that what he is saying here is that he likes a super smooth 48p fps look but when it comes to 24p fps he prefers a slightly more stuttery look than the norm. My opinion is that he is simply compromising between a high frame rate for 3D and a normal looking shutter speed for 24p. If he was shooting for 3D ONLY he would likely shoot 60P 1/120 second shutter. That could never be converted to a normal looking 24p though. If he was shooting for NON 3D only he would shoot at 24p 1/48th of a second, the industry standard. I believe that is because we are in a transition from old to new technology and he is shooting with both in mind; it’s a compromise."

http://www.videocand...pany.com/?p=224

Yeah, I believe that may have been a sad compromise and it won't completely realise the potential of 48 fps. Just simply by the look of the slower shutter speeds associated with video.

Some people don't mind that look though and Michael Mann certainly explored it with Public Enemies, David Lynch has done stuff with it. I'm not a big fan though.
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#10 Guillaume Cottin

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Posted 14 December 2012 - 09:07 AM

Interesting topic.
It's good to bear in mind that one can always *add* motion blur in post, while the contrary is not possible. By choosing a 1/64th shutter (and not 1/60th like I mistakingly wrote earlier), Lesnie stayed on the safe side : a 1/96th shutter (180 degree at 48fps) would probably have created a less pleasing look at 48fps, while making the 24fps conversion more difficult.

I wonder about the editing of 48 fps material. We know that a cut has sometimes to be frame-accurate.
Do 48-fps cuts also work seamlessly at 24fps, or is there some tweaking needed to adapt the editing for the lower framerate?
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#11 Philip Mayor

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Posted 15 December 2012 - 05:24 PM

I would think in very rare situations certain edits might not work, but they would be rare. If there's a strobing light or effect where every other frame records this effect in 48, then it's possible a 24 version could miss it entirely. Maybe more likely would be an optically created subliminal. If a director wants a one frame image of a skull in 48fps to scare the audience subliminally then there's only a 50/50 chance that image will make it into a 24 version. So in these types of cases extra care would have to be taken.

But you are absolutely right that in editing one frame can make all the difference, but one frame at 24 would be more critical than one frame at 48.
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#12 Oliver Hadlow Martin

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Posted 15 December 2012 - 07:10 PM

Can some explain to me something. Would there be any difference viewing 48fps footage on a 60hz (computer monitor) and a 4k 48fps projector? I'm assuming they run at 48hz? Or do they run higher and illuminate each from twice or something?

Basically what I'm asking is will 48fps look the same roughly from a computer monitor to a proper HFR projector.
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#13 Philip Mayor

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Posted 16 December 2012 - 08:29 AM

Well since there are sample clips of HFR footage on the Internet from companies promoting the technology then I'd have to say yes to your second question.
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#14 Frank Gollner

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Posted 17 December 2012 - 04:50 PM

There is another ingredient that needs to be factored in when discussing frame rates and that is the physiological aspect of human perception. There are two concepts I encountered when reading a book titled "The History of Narrative Film" Sadly I no longer have the book so I cannot recall the author, but as I recall the first chapter dealt with a brief history of human perception. Over the centuries, scientists psychologists and more recently neurologists have come to an understanding of how the human brain and eye, work together to enable us to see the world we see. On a very basic level I was introduced to two terms "Persistence of Vision" which is the brains ability to retain an image for a fraction of a second after the light has been absorded by the eye, and "Phi Phenomena" Using the books example, Phi Phenomena allows us to take a colour wheel painted with equal thirds, red, blue and green, spin the wheel at high speed so that the individual colours appear as completely white to the human eye. It is this same phenomena that enables 24 individual still images to be run on a projector at 24 frames a second, with the projected light passing through a shutter with a 180 degree angle that allows a frequency of 1/48th of a second. Anything slower than a frequency of 48, the human eye will perceive as flicker.

In fact this is where the generic term "flicks" that referred to movies or film in the early days of cinema came from. Because celluloid wasn't cheap, especially in the beginning and to save money, camera's were hand cranked at roughly two rotations of the handle a second, giving a rough speed of 16fps, well below the minimum of 48fps, which when projected back at roughly the same speed appeared to "flicker" when viewed by the audience on the big screen.

So it isn't just all just about the technology and what it can and can't do, it is as much about the physiological effect it has on the people watching as well that must be taken into account, I understand one of the benefits of filming and projecting at a higher frame rate is it places less strain on the peoples eye's when viewing in 3D.

To quote a personel example I couldn't understand why my Mum and Dad didn't want to see any recent films projected in 3D, I asked why, and they told me that when they watched 3D films in the 50's and 60's using the old antiquated technique of viewing through the old red and blue glasses it left them with a headache. It took me a while to convince them that the technology has moved on in 50 years, but the perception still lingered.
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