|Film vs. Video continued
Transferring film to video is accomplished with a telecine, which utilizes a "3:2 pulldown" to resolve the difference in frame rates between the two mediums. It takes more than a bit of fooling around to make 24 go evenly into 30, and no solution will yield motion that is identical to the original film. Because there are five video frames (or ten video fields) for every four frames of film, we must then derive ten fields from those four frames. If we simply to add those two fields at some random spot, we would slow down the movement at that point, but the 3:2 pulldown was devised to maintain smooth, consistent motion.
We accomplish this by creating a five frame repeating sequence of "whole" and "split" video frames. The "whole" video frames receive two identical fields from a single film frame, while the "split" video frames derive their first field from the already used film frame and then interlace it with a single field derived from the next film frame; this is done twice in a row in each sequence of five video frames. (Please refer to Figure 1).
When we talk of "look" of film, it is really film on tape that is being compared to tape that originates in a video camera. The slightly discontinuous motion created by the 3:2 pulldown is actually part of the look that we find so appealing.
Another motion characteristic that contributes to the special beauty of film is the blur that results from the camera shutter. The rotating shutter of a film camera typically opens for about 1/30th of a second, while the CCD of a video camera "opens" for half that time. The longer exposure duration of film causes its motion blur to be far more pronounced than video and this in turn increases the perceived smoothness of the motion.
The last aspects of the technology that we want to touch on are: colorimetry, dynamic range and tonal response; film origination has held all the cards as far as these particulars are concerned but this may soon change. Film offers dozens of unique stocks, each suited to different applications, with their own color rendering and contrast curves. Though individual video cameras have somewhat different looks, their signals generally conform to certain standards that do not reflect either the tonal qualities or contrast handling capabilities of film.
The latest generation of digital signal processing (DSP) video cameras offer many features relevant to those seeking the look of film. The Sony DVW-700WS, a Digital Betacam camcorder can not only handle the same dynamic range as a film camera, but it features a broad menu of user accessible image parameters that can be stored and retrieved from a small memory chip. Sony has configured set-up chips to match the color and tonal rendering of a variety of widely used film stocks; this is not to say that the output will look like film, but that it will match a particular stock in gamma and colorimetry.
Sony has marketed this camera for "Electronic Cinematography." They have packaged it with a film style matte box and motorized zoom control as well as making available an viewfinder extension and specially modified 16mm camera lenses. The "WS" stands for a 16:9 wide screen recording, a somewhat difficult to appreciate capability for 99% of the NTSC world, but it is becoming a more important format and is ideal for video to film projects.
A feature meant for theatrical release must currently be finished on film. But this reason to shoot film may become less of an issue as the marketing of films changes, and movie theater chains are already beginning to look seriously at video projection as a means of reducing their costs.
With all the differences between film and video, why go through the trouble to make one look like the other? The obvious reason is the look, but that very special look carries a host of associations along with it. Motion pictures have been penetrating our collective unconscious for 100 years. It is the natural point of reference for story telling, sitting in a darkened theater with hundreds of others, absorbing its slightly diffuse, dream-like quality. We also associate it with higher budgets and specific genres, such as commercials, rock-videos and episodic television.
The look of video has its own set of associations that include soap operas, infomercials, news footage, live broadcasts, instructional programs and low budget anything, not awful company, but definitely b-list. Video has a less subtle color palette, and often exaggerated edges, clipped highlights and strange artifacts. Video has a strong feeling of reality and immediacy, with a look that suggests its electronic nature.
We now have the background required for understanding the issues involved when we return next month and discuss the tools and techniques that can actually transform your dull, everyday video footage into something approaching the lushness of richly textured film footage. We will be examining production methodology, facilities that are specialized in creating the look of film, techniques that can be used in your current on-line suite, and software applications that will enable you directly on your desktop, including taking a first look at the amazing CineLook plug-in for After Effects from DigiDesign.