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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

What if i an Peter Jackson and want to shoot 48fps .

"So shoot 12 fps on really grainy film (can you find super 8 any more?) , and you'll have something really "filmic."

Nah, that's cool, 24 clean is fine.
 
Matthew Scott said:
Okay cool, thanks for the 101 lesson, not to be rude but I'm pretty sure most of us know that. The point is, the closer we get to the look of real life with higher fre rates, the further we get from a "movie". And, personally, I dot like the lookof fluid silky smooth movies. Next some director will try and mainstream 96fps....and then 120fps.....

Just saying, to me, personally, I like what my brain does with 24fps.
Click to expand...

Yeah... I'll be real careful next time not to offend you smart people.
 
James Brundige said:
Actually 1/36 second, so for 48 fps, that's 1/72. Correct?
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OK, let’s see if you’re right! http://en.wikipedia.org/wiki/Rotary_disc_shutter

“The primary reason that cinematographers adjust the shutter angle is to control the amount of motion blur that is recorded on each successive frame of film. A tight shutter angle will constrict motion blur. A wide shutter angle will allow it. A 180° shutter angle is considered normal.

So for instance, at 24p (actually 23.976 frames per second) the "Frame Interval" value is 0.04171 sec. ( = 1 / 23.976 ). Using an "Exposure Time" of 1/50 sec. we get a "Shutter Angle" value of 173°, very close to 180° (normal motion blur effect).”

I would say that a Shutter Speed of 1/32 Second - 270° Shutter Angle for S3D @ 48 FPS, you would lose One T Stop from 24 Fps. The formula is posted on the Wekipedia reference. Check it out.

Humberto Rivera
 
I just read you post again. It’s 1/32 of a second for both 48 Fps and 24 Fps, it’s the T Stop that changes.

Humberto Rivera
 
I was just reading in http://en.wikipedia.org/wiki/24p the following reference;

Future

“Next generation digital cinema equipment is being designed to also handle the 48p frame rate[citation needed] along with the traditional 24p. 48p has twice the (video-like) motion (temporal resolution) of 24p, but also requires more bandwidth, data storage, and potentially illumination level. Peter Jackson's two part film The Hobbit is one of the upcoming productions which will make use of the 48p frame rate [6].

Some current, best-of-breed professional video cameras provide 120 frame/s progressive capture, which is 5 times 24p and can be converted to 24p, 30p, 50i, and 60i/p with editing options and precision in motion shots. [7]”

Interesting

Humberto Rivera
 
Humberto Rivera said:
Shutter Speed of 1/32 Second - 270° Shutter Angle for S3D @ 48 FPS

Humberto Rivera
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Humberto Rivera said:
Let’s start with a wide open shutter @ “360°” shutter angle, which is “1/24” of a second, shooting at 24 Fps with a 180° DEGREE SHUTTER ANGLE (1/48 SECOND), so a 270° shutter angle is between the two or 1/32 Second.

Humberto Rivera
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This is incorrect.

Shutter angle is a relative shutter speed measurement ... and its relative to frame rate. So, what a 180º shutter means changes when you change frame rates.

At 24 FPS a 360º shutter = 1/24th of a second. 180º = 1/48s.

At 48 FPS a 360º shutter = 1/48th of a second. 180º = 1/96s.

To answer the earlier question 270º shutter, which is what the quote above indicates Jackson & Lesnie are shooting Hobbit at, at 48 fps is 1/72 ... so long as they keep shooting 48fps! There is slow motion photography in The Hobbit. If they are shooting 120fps for slow motion, then 270º shutter will be 1/180s.

The equation for calculating exposure time given frame rate and shutter angle is:

T= 1/(S*360º/a)

Where T= Time of exposure, S=frames per second, and a = shutter angle in degrees. You can find this in the ASC manual on page 615.

For completeness, the fraction of a second shutter speeds common in photography and ENG are absolute shutter speeds.
 
Alexander, let’s see if we can answer the question, first what Peter Jackson said;

“Converting a film shot at 48 fps down to 24 fps is not a hugely difficult process, but it requires testing to achieve the best results. Some of this involves digital processes during post-production. We are also shooting the film a slightly different way, which is a question several of you asked. Normally you shoot a movie with a 180-degree shutter angle. Changing the shutter angle affects the amount of motion blur captured during movement. Reducing the shutter angle gives you the stroby (or jerky) "Saving Private Ryan" look.” “However, we're going the other way, shooting at 48 fps (48 Fps Known) with a 270 degree shutter (270º It is Known) angle (What is the T Stop? Not known!). This gives the 48 fps a lovely silky look, and creates a very pleasing look at 24 fps (The Shutter Speed is the Same! It has already been shot so it can’t change) as well. In fact, our DP, Andrew Lesnie, and I prefer the look of 24 fps when it comes from a 48 fps master." Peter Jackson - (In between parentheses by Humberto)

OK, I hope we can agree on the above statement, I also agree with you on the two samples you sited below;

At 24 FPS a 360º shutter = 1/24th of a second. 180º = 1/48s.
At 48 FPS a 360º shutter = 1/48th of a second. 180º = 1/96s.

So the only question is; is-it 1/32 or 1/72 for a 270º Shutter, that’s the question? Now on the formula from the ASC Manual; T= 1/(S*360º/a) Where T= (1/32 or 1/72) Time of exposure, S= (48) frames per second, (*360º), and a = (270º) shutter angle in degrees. I’ll get back on this one latter, I’ve got to think about it.

I want to thank you for your message, it makes me think, I usually try and say that it-is in MY OPINION, however in this case it got to be one way or the other, it’s always good! I see that you’re like me; you get up early in the morning to check RedUser.com, I usually get up at dawn to see the Sun rise over the East.

Humberto Rivera
 
OK Alexander, let’s try again, if both of these two statements are accurate; at 24 FPS a 360º shutter = 1/24th of a second. 180º = 1/48s; and at 48 FPS a 360º shutter = 1/48th of a second. 180º = 1/96s. There is NO reference to what T Stop was used.

Then a shutter speed between 360º and 180º is 270º, it’s between the two, I don’t know if you agree with that statement, but that’s my position. Therefore 1/32 is the correct shutter speed, 1/72 would be right for anything above 180º (actually a lower value).

I think that any differences is adjusted by the T Stop, such as taking One Stops off for shooting in S3D, or a difference in shutter angle such as 270º @ 48 Fps, or the lighting on the set, or whatever. Having shot the film at a 270º shutter angle @ 48 Fps that means that is the recorded frame rate, a 24 Fps 2D version of the film cannot change the Shutter Angle because it’s been recorded in the Meta Data. So the 24 Fps and the 48 Fps use a little more Motion Blur than the ideal 180º.

Anyhow, that’s how I see-it. Please tell me if you agree or disagree with my logic. I thought about-it for a while.

Humberto Rivera
 
Jeezus guys, it's not that difficult...it cant be 1/32, because THATS LONGER THAN 48FPS FRAME RATE COULD ALLOW
the shutters open for 3/4 of each frame, so 48/.75 = 64...it's 1/64th of a second exposure time

The 2D version of the show will just be dropping every second frame, but it STILL GIVES YOU 1/64th of a second exposure time, equivalent to a 135 degree shutter, so slightly less motion blur than you're used to but not really noticeable, as you can see from the first trailer.
 
John Allardice said:
Jeezus guys, it's not that difficult...it cant be 1/32, because THATS LONGER THAN 48FPS FRAME RATE COULD ALLOW
the shutters open for 3/4 of each frame, so 48/.75 = 64...it's 1/64th of a second exposure time

The 2D version of the show will just be dropping every second frame, but it STILL GIVES YOU 1/64th of a second exposure time, equivalent to a 135 degree shutter, so slightly less motion blur than you're used to but not really noticeable, as you can see from the first trailer.
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Indeed. Just did the calculation myself: http://en.wikipedia.org/wiki/Shutter_speed#Cinematographic_shutter_formula 48x360/270=64.
 
I still have a lingering question because of what Peter Jackson said; “48 fps with a 270 degree shutter angle.” Isn’t a 270° (1/32) angle shutter, half of 135° degrees or 1/64 of a second. Maybe someone can please explain that for me, I’m a bit confused. Thank You!

Humberto Rivera
 
Humberto Rivera said:
I still have a lingering question because of what Peter Jackson said; “48 fps with a 270 degree shutter angle.” Isn’t a 270° (1/32) angle shutter, half of 135° degrees or 1/64 of a second. Maybe someone can please explain that for me, I’m a bit confused. Thank You!

Humberto Rivera
Click to expand...

Shutter angle is a relative term, shutter speed is a fixed term. Shutter angle is based entirely off of the frame rate whereas shutter speed is independent of frame rate. I.e. 24fps @ 360º shutter means the shutter is open the entire time 1/24th of a second (in this case). If your base frame rate is 60fps then a 360º shutter means that your shutter speed is 1/60th of a second.
360º the shutter is open the entire frame, 180º the shutter is open 1/2 of the frame, so if your frame changes and you keep the same shutter angle your shutter speed changes as well.

Hope that helps.
 
OK, let’s see if I have this right, he is shooting at 1/64 of a second, with a 270º degree angle shutter? Is that right? I’m just trying to understand. Thank You!

Humberto Rivera
 
Humberto Rivera said:
OK, let’s see if I have this right, he is shooting at 1/64 of a second, with a 270º degree angle shutter? Is that right? I’m just trying to understand. Thank You!

Humberto Rivera
Click to expand...

Yup, 48fps @ 270º shutter which = 1/64s shutter speed.
 
One more question! Then the shutter angle of 270º is going to give him the same “Motion Blur” that you normally get from a 270º degree shutter, but at 1/64 of second? Does the “Motion Blur” come from the shutter angle or the shutter speed? I’m really trying to understand. Thank You!

Humberto Rivera
 
Humberto Rivera said:
One more question! Then the shutter angle of 270º is going to give him the same “Motion Blur” that you normally get from a 270º degree shutter, but at 1/64 of second? Does the “Motion Blur” come from the shutter angle or the shutter speed? I’m really trying to understand. Thank You!

Humberto Rivera
Click to expand...

Shutter angle and shutter speed are two ways of describing the same thing.

As for motion blur I asked a similar question a while back: http://www.reduser.net/forum/showth...r-Speed-high-fps&highlight=high+speed+shutter
 
The amount of motion blur potential is relative to the time the shutter is open, whether expressed in time increments or angle.

In the case of 1/64th of a second, 270° at 48fps, the blur would be more then shooting 48fps at 180° (1/96th) but less than 48fps at 360° (1/48th).

What I am interested in is finding the right combination of playback rate and motion blur that gives me a "clean" look without objectionable judder.

For example, if I shot a thin shutter like 1/500th at 24 fps it would almost certainly look choppy unless there was very little movement. If I could play back at 240fps I would expect it to look smooth even if there was fast camera moves or fast moving subjects. What I want to figure out is how thin (fast) of a shutter I can use at 48 fps and maintain "smooth" motion.

I can well imagine that the 1/64th that PJ is using is a good combination for lighting demands, blur amount and of course 3D immersiveness (is that a word?)

Perhaps even at 48 fps anything thinner than a 180° shutter will still look choppy. Perhaps I should just look up Doug Trumbull, buy him a beer and pick his brain...

Cheers - #19
 
Thank for the reference Tehben, I’ll sleep on that tonight, and read it again in the morning! I’m going to try and understand Mitch Gross explanation.

Humberto Rivera
 
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