Film has truly been the medium to create some of the most beautiful pictures. Many unique characteristic of film all contribute to an overall effect that has been given the accolade of "film look". The single most significant contributor to the "film look" is the effort and care in lighting and production that are typical of a film production. It seems intuitive that if it is desired to create equally beautiful pictures using electronic acquisition, it is mandatory to allocate the same artistry, lighting, and production resources to a digital production as would be allocated to a film production.
When we further analyse the "film look" we recognise many characteristics of film that are similar to electronic acquisition and several other characteristics of film that differ from electronic acquisition; some of these differences are discussed in more detail below. What is definitely true is that if the same care and effort is expended in the production, each medium produces equally beautiful pictures albeit there may be a different "look".
The Film Look set-up cards have been designed to suit users that wish to get closer to the look of film, as well as those users who wish to shoot a portion of a production on film and to shoot other portions digitally to facilitate extensive digital manipulation in post production. When the appropriate Film Look Digital Gamma is installed in the DVW-700WS the electronically generated segments will tend to integrate more smoothly into the portions generated on film.
A comparison of recordings made directly on the DVW-700 and video that has been originated on film, most generally 16mm or Super16 film can be summarized as below:
• Exposure latitude
This term generally encompasses two concepts:
Dynamic Range, the ability of the camera to capture the very large difference between the brightest and darkest parts of a scene, often found in outdoor shooting with uncontrolled lighting. In this parameter the DVW-700 camcorders provide outstanding performance that can often exceed the performance of video originated on film. The black to white response of the DVW-700 is defined by a 32 point digital look-up table, so that it is possible to carefully define a S-shaped response in the camera that acts very much like a film knee in handling severe highlights. A slight overload causes very mild compression a more severe overload causes progressively more severe compression. Although the film negative has a superb ability to capture a very wide dynamic range, most of the existing film to tape transfer devices have not evolved to the same degree and do not offer the sophisticated signal processing of the DVW-700, as a consequence the superb dynamic range of the original negative is not always fully transferred to video.
The second aspect of exposure latitude, is the ability of film to recover an excellent picture from the negative, even when the actual exposure used is incorrect by a significant amount. Consequently, film is perceived as a "forgiving" medium and under exposures and particularly over exposures are recoverable to a large extent. In this aspect, film can outperform electronic acquisition, but the gap is closing. The electronic camera is able to provide significant electronic assistance, such as zebra indication to help the operator choose the correct exposure and the special set-up cards included in the BSC-1F1PACK include a provision to significantly increase the ability of the DVW-700 to recover from an actual error in exposure. See the description of the special set-up cards in the BSC1-F1PACK above.
• Comparable resolution
Transfers from film generally use a minimum of edge enhancement. The DVW-700 intrinsically provides such excellent resolution (i.e. Depth of Modulation) that it is important to use a very low setting for the edge enhancement (detail amplitude), to provide a cinematic look, i.e. the picture quality and feel of a film transfer. The lack of grain and the ability of the electronic camera to create a more "life like"
picture is frequently attributed to resolution only, but each of these effects provides a distinct contribution to the overall look of the picture. The set-up cards contained in the BSC1-F1PACK provide a black to white transfer characteristics very similar to the most commonly film emulsions and thereby help to converge film transfer and direct acquisition.
• Comparable color reproduction.
The spectral characteristics (also called taking characteristics) of the film to video conversion device (telecine) are typically very similar to those of an actual video camera. In video material that has originated on film, the spectral characteristics of the actual film emulsions is superimposed on the spectral characteristics of the telecine. Since direct acquisition involves only the taking characteristics of the video camera, the color fidelity that can be achieved via direct electronic acquisition, is typically of equal or superior quality than a film transfer. The DVW-700 includes a device called a "linear matrix", that allows the colorimetry provided by the DVW-700 to be adjusted. The Setup Section provides settings for the linear matrix that allows the DVW-700 to match the colorimetry of the commonly used film emulsions, or to create a colorimetry that is as faithful as possible (per standard CCIR-709) and that has been judged to be very beautiful. Please note that the intrinsic colorimetry of the film emulsion used, is frequently altered after transfer by the operator of the color corrector. Use of a color corrector is virtually mandatory with film to remove slight imperfection in the three film emulsions, but if the colorist provides an artistic contribution to the final footage, it is important that material acquired directly on the DVW-700 receive the same artistic contribution provided the film originated material. In most cases the serial digital output (SDI signal) of the Digital Betacam playback (CCIR-601) is identical to the output of the telecine and can be applied directly to the input of a color corrector.
• Different Texture
Film has a granular structure that is a significant contributor to the overall effect we call "film look". The DVW-700 Digital Betacam provides low noise recordings even when extra sensitivity (gain boost) is activated. Since the usage of original camera material can be for many different applications, it is not desirable to generate "film grain" in the camera originals, but to mix such an effect into the camera material in post production (although it must be acknowledged that devices to do this effectively are not commonly available at this time). Film grain on the other hand may become an impediment to the successful transmission of programming to the home using the new digital broadcast system and the high compression ratios necessary.
• Different picture stability
Film has inherent picture weave - Digital Betacam delivers rock steady pictures. We can again invoke the argument above that the camera original should not contain such an effect. It is not inconceivable that a time-base corrector that has the ability to transform an unstable time base to a rock steady picture could be adapted to work in reverse and introduce gate weave into a rock steady picture. This effect needs to again be used with caution not to impair the material from being compressed successfully for future digital transmission.
• Different motion capture
In this aspect film and video acquisition differs most significantly. Film captures 24 frames per second and the iris is typically open only 50% of the time (180 degree shutter). The DVW-700 on the other hand captures 30 complete pictures consisting of 60 interlaced fields, where the "shutter" is essentially always open. Fast motion of the camera or the subject, is captured much more successfully by the electronic camera, but the "look" of 24 frame film converted to video is unmistakable and an essential ingredient of the famous "film look". To truly imitate this effect of film, may require the development of electronic cameras that provide frame based acquisition at film rates instead of the current interlaced field acquisition at 30 frames a second.
Copyright © 08/25/97- Sony Electronics, Inc.
Peter Gloeggler - Product Manager - Camera Products
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