Everything you ever wanted to know about HFR and The Hobbit

By Tim Dashwood, Dashwood Cinema Solutions

Hobbit HFR 3DThe Hobbit has finally been released in 2D and 3D at the traditional 24 frames per second (fps) as well as 3D High Frame Rate (HFR) at 48 fps. If the posts on social media are a fair indication, it seems that audiences have not reacted as positively to the 3D HFR version as the industry had hoped. Why not? Industry leaders like James Cameron, Douglas Trumbull and Peter Jackson have been been telling us why HFR is a better choice for 3D (and 2D) by overcoming one particular technical issue that may cause viewer discomfort, and they are absolutely correct in that respect. However, HFR will not solve all the potential eye-strain problems associated with a 3D presentation, and the film-going public has become accustomed to the aesthetics of 24 fps as a key contributor to the cinematic look of their favourite films. To most, the hyper-realism of 48 fps seems like a strange intruder in the context of an epic fantasy film like The Hobbit. Battle-lines are being drawn between the technical improvement of HFR and the aesthetic “feel” of the traditional 24 fps film standard.

Why haven’t we always used a higher frame rate?

Historically, 24 fps came about at the dawn of “talkies,” when the typical frame rate of film was only 18 fps. 24fps was the minimum speed required to successfully play back sound tracks in sync with the picture. When you consider that a 1000 foot roll of 35mm film only represents about 10 minutes of screen time, is expensive to purchase and process, and weighs around 5 pounds, it makes logical sense that filmmakers and studios made the choice to standardize the slowest frame rate necessary for sound. Scientifically speaking, studies have shown that humans’ threshold for equivalent fps in real life is somewhere around 60 fps, so the unintentional side effect of 24 fps is an ‘other worldly’ sense that a film is a film and definitely not real life.

The slow frame rate had no ill-effects in the infancy of film because the camera was typically wide and stationary. However, when filmmakers like G.A. Smith, Giovanni Pastrone, Allan Dwan and D.W. Griffith started moving the camera, it became apparent that, because of the flicker and low frame rate, slow controlled “push in” or “pull out” moves were far more pleasing to the viewer than fast pans or side-to-side dolly moves.

The bump up from 18 fps to 24 fps didn’t help very much with this issue and soon pan speed charts were published by organizations like the American Society of Cinematographers.

These charts are still published in the ASC manuals and professional cinematographers still refer to them. If I reference a typical example in the ASC chart I see that a 90 degree sweep of a static scene at 24 fps with a 35mm lens should not be performed in less than 18 seconds (whip-pans being the exception). However, the same pan with the same setup at 48 fps can be performed in half the time at 9 seconds.

There are always exceptions to these ‘rules’ but the point is that it makes logical sense to shoot and project at a higher frame because it frees the filmmaker to shoot faster pans with less “judder” and faster action with less motion blur.

Douglas Trumbull created an HFR 60 fps system a long time ago called Showscan, but it never took off for mainstream production because of the inhibitive costs associated with all of that film. Filmmakers have always had to find ways to fit their creative requirements within the technical limitations of the medium. HFR digital acquisition is supposed to remove one of those limitations, but it can only truly do that if HFR is also used in digital projection.

The technical limitations of the medium are even more restrictive when working in stereoscopic 3D (S3D), especially when it comes to frame rates. The S3D illusion requires parallax points for each object in the scene to be visible to each eye, which is almost impossible in scenes with fast movement (like sword fights) where key parallax point practically disappear due to motion blur. When panning in S3D the brain must work even harder to link the images from the two views and the judder effect is compounded further by current S3D projection technology.

If you have the chance to watch both 24 fps and 48 fps HFR versions of The Hobbit you will see feel the eye strain in the large and fast sweeping shots at 24 fps, but it will feel smooth and effortless at 48 fps.

Knowing how higher frame rates can improve this important aspect of S3D and free filmmakers constraints, it makes sense from a technical perspective that the S3D industry would push for higher frame rates, especially now that digital acquisition and digital projection remove many of the financial detractors. But will audiences accept the radically different look and feel for narrative films like The Hobbit, or is it better suited for nature documentary, concerts, theatre, theme parks and sports? Frame rate plays a big role in the psychological perception of what we are watching. [more...]

Source: Dashwood Cinema Solutions

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