Shooting with EPIC at 48p for 24p viewing?

[Brian Iannone]

After watching the behind the scenes videos on The Hobbit, there's one thing I don't completely understand. If you shoot at 48 fps with a shutter speed of 1/96 seconds, will the footage look strange if you convert it to down to 24 fps (i.e. for a Blu-ray disc)? If you do that, then wouldn't you have footage at 24 fps in which each frame was captured at a shutter speed of 1/96 seconds? I thought that this goes against the 180 degree shutter rule?

The reason I ask is that most of what I'll be shooting is stock footage and short documentary-style films. So, my final files will typically only need to be at 24 fps. Would shooting at 48 fps instead be a better idea? If so, what shutter speed should I use?

 

[Cail Young]

They're shooting 270° on Hobbit to combat this for 24fps release.

 

[Damien Molineaux]

They're shooting 270° on Hobbit to combat this for 24fps release.

Well for precision purposes, as they're not using a rotating shutter, you can't really say they're shooting at 270° but the equivalent of, which would be 1/72nd of a second.

Good info by the way, thanks.

Cheers,
Damien

 

[David Didato]

270 at 48fps would be 1/64.

 

[Imran Farouk]

So would it be 1/64 or 1/72

 

[Brian Iannone]

Wouldn't it be 1/72? That seems like it's in between 1/48 and 1/96. Or, is it 1/64?

 

[Thor Melsted]

270 degrees is halfway between 180 and 360, so if the shutter angle is 270, then logically the shutter speed would be halfway between 1/96 and 1/48, which is 1/72.

David, how did you arrive at the 1/64. Am I missing something?

 

[Charles Wood]

This is a great question. I was wondering this myself when Jim Cameron mentioned that Avatar 2 and 3 would be shot at 60 so they could easily accomodate 60p television and distribution in the future. But that means a 1/120 shutter speed.

I don't know if any of you saw Douglas Trumball's presentation at NAB this year, but he has a solution to the framerate/shutterrate conversation that I thought was out of this world cool: ShowScan Digital

http://www.youtube.com/watch?v=NkWLZy7gbLg

Basically, different elements WITHIN THE PICTURE would move at different framerates:

Example: A ninja fights another ninja with fast kicks and hits. The arms and legs are being displayed at 60p, while the less moving bodies and backgrounds are displayed at 24p.

The demo was kind of amazing.

 

[Imran Farouk]

So when you actually pull the 48fps down to 24fps wouldn't it mean a slow down in footage? or is this a similar operation to the whole 30fps to 24/25fps on the 5D M2 that I heard about?

Obviously be great to display things at 48fps, problem is that not every cinema, at least around me, is going to be readily able to show 48fps...

So wouldn't the clarity and all discussed for 48fps be lost in the conversion down to 48fps?

 

[John Allardice]

So when you actually pull the 48fps down to 24fps wouldn't it mean a slow down in footage?

Its accomplished by just dropping every second frame...but since the original frames are shot with a 270 degree shutter, the resulting image sequence will look like a standard 24fps movie shot with a 135 degree shutter, a little skinny, but not excessively so.

 

[Björn Benckert]

So when you actually pull the 48fps down to 24fps wouldn't it mean a slow down in footage? or is this a similar operation to the whole 30fps to 24/25fps on the 5D M2 that I heard about?

Obviously be great to display things at 48fps, problem is that not every cinema, at least around me, is going to be readily able to show 48fps...

So wouldn't the clarity and all discussed for 48fps be lost in the conversion down to 48fps?

No the conversion is easy you just throw every second frame away and viola you have 24p again.

Shutter speed is not needed to be 180 degree or half a frame all the time. It's very possible to shoot at shorter or longer shutter speeds than half a frame on a digital camera like the epic so doing a film in stereo 48fps you would be able to shoot 360 shutter and have the same motion blur as in normal 24p then when you convert to normal 24p and you trough half the fames away you end up in normal 180degree motion blur. So what Peter Jackson is doing is that he almost shoot at 360 degree shutter so he has a very normal motion blur but he also has twice the frames. The less frames you have per second in playback the more motion blur you need basically.

 

[Brian Iannone]

Thanks everyone for the replies. It's really great to have so many experts in cinematography here. =)