Why Are We Still Filming In Framerates Designed In The 1920's?
I remember a conversation with a cameraman who shoots all his footage in 24p, because this way it can easily be transferred to film at some point. He says using 24p mode helps to achieve a 'film-like' look, most film cameras and projectors are designed to show 24 frames per second.
Personally, I wish we could move on and start filming in 60p already. I'll try to explain why.
Shutter Times and Motion Blur
In the still frame from the movie Tomb Raider below, you can see that Lara looks quite blurry. Because the camera operator used a long shutter time, Lara moves a certain distance during every single exposure.
If this scene was captured by a video camera with a very short shutter, this still image would show Lara 'frozen in time', but the motion appears jerky when you watch the movie because only 24 frames are shown every second.
Filming with 24 frames per second has it's limitations. Todd Terry, creative director at Fantastic Plastic says:
"Film has been shot at 24fps for darn near 100 years. It is 'stuttery', just as much as 24p video. One of the chief differences is, cinematographers used to shooting 24fps know exactly how to do it. Fast pans, the wrong kind of action crossing the frame at the wrong rate, etc., will yield just as must stutter as video."
In movies, tracking shots and camera movements are often used in conjunction with short depths of field, which help by softening backgrounds that if moving at different speeds to the tracked subject would otherwise appear to jerk and stutter.
But also on television, during camera pans to follow the action at sports events, HDTV trial viewers reported nausea while looking at the smeared images. In practice compromises such as slower panning and deliberate softening of the images are used to fix this.
High Frame-rate Television research
In the 1980's it was already recognised that higher framerates would improve the portrayal of moving objects. Subjective tests have been carried out with framerates of 80 fps, using high speed camera pans. Increasing the frame rate to 80Hz resulted in a considerable subjective quality improvement.
In 2008 the BBC did some research on 'High Frame-Rate Television'. The frame and field rates that have been used for television since the 1920s cause problems for motion portrayal, which are increasingly evident on the large, high-resolution television displays that are now common. When picture resolution increased with HD television, the differences between sharp objects and blurry moving objects became much bigger than on lower resolutions.
There have also been experiments with high speed film cameras and projectors. In the early 1980's, Douglas Trumbull experimented with filming and projecting movies at 60 frames per second, 2.5 times faster than standard movie film. This renders a dramatically smoother and more realistic rendering of motion. Trumbull found that as the frame rate increased, so did the viewer's emotional reaction.
BBC Research and Trumbull have successfully demonstrated that increasing the frame rate can significantly improve the portrayal of motion, even at standard definition. One of the limitations currently is that when frame rates increase, data storage will increase too. Fortunately, when more frames per second are recorded, data compression will become more efficient as there is less variation between frames.
Another important reason we are still looking at 24, 25 or 30 frames per second is compatibility. When HD resolutions became mainstream, it was decided that it was better to keep using the traditional framerates to make the transition easier. Your footage can be broadcast everywhere in the world in 25 fps (PAL) or 30 fps (NTSC) without the need for expensive hardware conversion. Broadcasters have just upgraded their hardware to support HD footage, and it will take a long time before they are ready to replace their hardware again.
Plans for filming Avatar sequels in higher frame rates
James Cameron, the director of the Avatar and other films has announced his plans to film Avatar sequels in 48 or 60 frames per second. Cameron says that this will make a visit to movie theaters a very unique experience.
Cameron is working with projector companies like Christie to explore what the possibilities are. Not just for 3D movies, but for all movies. The capabilities are already available in today's digital cameras:
"We have done tests ourselves with different digital cameras and proven that they can all shoot at the higher frame rates. They all could, but they alway utilize it for slow motion. They will record something at 48 or 60 frames per second, but when they play it back at 24, they are doing slow motion. Now we want to do it, but play it back at those same rates."
"When you author and project a movie at 48 or 60, it becomes a different movie. The 3D shows you a window into reality; the higher frame rate takes the glass out of the window. In fact, it is just reality. It is really stunning."
Altough I'm not a big fan of 3D movies, I can't wait to see the results. This will make a big impact on movie quality and immersion, maybe even more than what 3D has brought us.
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