Peter Jackson has stirred some controversy when he announced that he will be shooting The Hobbit at 48 frames per second (fps). Film purists are crying out loud in face of that “crime”. Stu Maschwitz – who I highly respect – has been a proponent of 24 fps for years and a clear, laid back opinion on the topic. With all due respect I have to argue …
One often heard argument is that 30, 50 or 60 fps are a bane of video and diminishes production value. Stu argues that audiences have rejected shows shot at such framerates. I think the argument falls short and there is much more to it than framerate. Shooting on video is the main culprit. Video has much less dynamic range than chemical film (only recent developments rectify that). Also, the 180° shutter in film cameras has a very specific optical quality (due to the mechanical workings and the 1/48 sec exposure). Video with their CCDs and CMOS chips often has been exposed at 360° thus exhibiting a very different quality in motion blur. Furthermore CCDs (the predominant form of sensors for a long time in the video world) are read line by line – resulting again in a very distinctive look due to the temporal shift from the top to the bottom of the frame. Video also more often than not is shot interlaced as that is the format which is broadcasted. All that contributes to the “video look”. Framerate is just one aspect – though still an very important one.
I think we agree that film is becoming a rare beast in production and the shift to digital is almost complete. So we already witness a change in optical shutter quality (a rotating disc versus digital sensor readouts). While a film camera would not be able to expose at more than 180° our new digital cameras can. Still, almost every DOP (director of photography) would pay attention to follow the 180° shutter rule to keep the film look and we all should be thankful for that. Opening the shutter for more than 180° would increase the motion blur. This would mash up the picture tremendously. So we end up in the digital world shooting “film” that very closely looks like what we have been used to for many decades.
By wanting to keep the film look the framerate is also kept at 24 fps. Quite understandably so. Though with that decision (or lack of decision to change it) come all the shortcomings of film. Fast pans can start to judder or strobe. The same is true for fast motion. Still, most DOPs and directors have not thought about using different frame rates. Quite understandably so as it would result in a very different look, would it not?
That’s the point where I think Peter Jackson really made a smart move. He is shooting at 48 fps – double the framerate. This might sound insignificant and I’ve heard arguments why not 50 fps like with PAL or 60 fps like with NTSC. I argue that 48 fps have a dramatic consequence over those frame rates considering a second aspect: shutter angle.
Filming at 48 fps with a 360° shutter will give you a frame that is indistinguishable from a simultaneously shot frame at 24 fps with a 180° shutter. Both frames have an exposure of 1/48 second. Both sensors will have the same amount of light hitting them. Both frames will exhibit the same amount of motion blur. On a frame-by-frame basis they will be identical. The only difference – which still might be considerable – is this: shot at 24 fps you blank for 1/48 second every frame. You essentially miss half of what is happening. At 48 fps you fill in those 50% of missing time. You get the whole picture, so to speak.
Also, think about this: In cinemas film has been projected with shutter rates of 48 or even 72 Hz to reduce flicker for a long time. So what has been recorded at 24 fps has been projected at 48 fps for good measure. Film has been mangled through a 3:2 pulldown (NTSC) or sped up by 4% (PAL) for DVD and TV release and shown at 50 or 60 interlaced frames. Still, movies have retained the “film look” after all that torture. Yes, it still has been recorded at 24 fps at 1/48 exposure. I argue that recording at 48 fps at 1/48 exposure will retain the film look and getting rid of judder and strobing which should come at great relief -especially when projected in stereoscopic 3D.
Just one note: I don’t know what shutter angles Peter Jackson is using on The Hobbit. Somehow I have the gut feeling that a 360° shutter would be a logical choice to make regarding lighting requirements, motion blur quality, speed of lenses etc. … Just saying 
Update April 26th, 2011: Peter Jackson posted on Facebook that they are shooting at 48 fps with a 270° shutter (translating to a 135° shutter at 24 fps). So it’s right between the traditional 180° and my speculation of 360°. Smaller shutter angles have been used before on film @24 fps as well (giving that very crisp, strobing look). I for once am curious how The Hobbit will look.