09.17.2003 12:00 AM
Studio Cameras: 20 Years and Growing
Moore's Law helps make bring higher resolutions to imaging technology
PARK RIDGE, N.J.
In 1983, the 30mm Plumbicon photoconductive pickup tube reigned supreme as the epitome of high-end imaging for top-of-the-line studio cameras. The smaller 25mm sister tube had become dominant in Outside Broadcast (OB) mobile trucks. And, fresh from half a dozen years of phenomenal success in electronic newsgathering (ENG), the upstart 2/3-inch pickup tube was just daring to challenge these 20-year-old industry mainstays in the sacrosanct studio domain.
Twenty years years later, the 2003 studio/OB camera landscape is comparatively unrecognizable-in terms of the quite extraordinary performance and sheer technological sophistication of presently available products.
TECHNOLOGY SPEEDS UP
Two decades ago, that daring entrée of the highly compact 2/3-inch pickup tube saw the initiation of a marked acceleration in both the technology and the ergonomic innovation in studio camera design-the 2/3-inch pickup tube was destined to rapidly unseat the long entrenched larger imagers. By the late 1980s, the tube had achieved a remarkably high level of performance-and, more importantly, a significant market penetration.
However, its glory days were to be short-lived. The 1984 debut of the RCA Charge Coupled Device (CDD) imager triggered an explosive competitive race into the new era of the solid-state imager. In rapid succession, NEC, Sony, Philips, Hitachi and Ikegami all introduced 2/3-inch CCD camcorders for ENG. By 1988, the photoconductive pickup tube portable camera was in rigor mortis, the first EFP cameras based upon CCD technology were appearing, and the signals were patently clear that the CCD studio camera was poised to make a dramatic debut. And, indeed, it proved to be so.
But, the legacy of the 2/3-inch image format itself was to prove unusually durable. Twenty years later, that image format size is the undisputed and unique global standard for virtually all HDTV and SDTV high-end studio cameras.
Separately, at NAB 1984, the world's first commercially available High Definition Television (HDTV) studio camera made its debut-together with an analog HDTV VTR and HD studio monitor and a projection system. The camera was based upon a 25mm Saticon pickup tube. Within a year the SMPTE and the ATSC were mobilizing hundreds of industry experts to begin what ultimately transpired to be a 12-year "long march" to HDTV standardization-for both production and terrestrial broadcasting. An entirely new impetus had been added to the technological development of the high-end studio camera-in the form of a very high bar in picture performance that had become an ever-pervasive presence. The mid-1990s saw the splintering of the marketplace into two distinct tracks-namely, SDTV and HDTV. At the same time, other technologies were looming.
DAWN OF DIGITAL
The dawn of the '90s spawned the digital camera. Global developments in Digital Signal Processing (DSP) had advanced with extraordinary rapidity at both the consumer and the professional level. Introduced with 8-bit A/D conversion following the CCD imaging system, these RGB video processing circuits brought something new and important to the complexities of the video camera-namely, stability and reliability.
Later, digital video signal processing of a sophistication that could never have been implemented in the analog domain was introduced. Creativity-at the hands of the video operator-was to be very substantially augmented. By 1995 the 10-bit A/D had arrived in SDTV cameras-and by 2000 it was 12-bit. DSP microcircuits were in excess of 2 million gates and the nonlinear digital video processing was being computed at 24 bits and higher.
Close on the heels of SD, HD camera technology had picked up serious steam. The year 1992 heralded the seminal arrival of the 25mm high-definition CCD imager and HDTV was never to be the same again. The digital pursuit of motion picture film was now seriously underway, except for one key issue: The ubiquitous 2/3-inch image format was destined to ultimately eclipse the 25mm format. And, by 2000 HD studio cameras had achieved 10-bit capability-and 12-bit by 2002. The analog camera was now totally and irrefutably relegated to posterity.
The industry recognition that digital had inexorably arrived sparked industry standardization activity in 1988, directed at defining and specifying the future all-digital HDTV camera chain. The all-important communication link between the camera head and the Camera Control Unit (CCU) was defined within the SMPTE to be a 10-bit digital 1.5 Gbps two-way link. Recent "revisionist theory" has, however, produced HD studio/OB camera systems based upon a simplistic plug-and-play analog triax cable intermediate link between the digital HD camera head and the digital camera CCU. The industry at large has, as a consequence, been thrown into some confusion.
The SDTV studio camera of today is endowed with quite astounding picture performance compared to those of 20 years ago. Back then, a signal-to-noise ratio of 55 dB (measured unweighted over a 4.2 MHz bandwidth) in an SDTV camera was considered breathtaking. Today, it stands at 66 dB and is still inching upward. Horizontal resolution-ever the singular yardstick of studio camera performance-can today exhibit a typical 80 percent depth of modulation at 400 TVL/ph (with no image enhancement) compared to the best of 55 percent of the former top of the line PbO pickup tubes.
The HD studio camera has surpassed the SDTV studio camera in a number of respects, but none ranks more important than the downconverted 4:2:2 digital SDTV output from the HDTV camera. It exhibits a higher depth of modulation (in the useful video passband) and lower aliasing-in both the horizontal and the vertical domain-than the best of the native SDTV cameras. And, with a pricing premium of perhaps 30 percent over that of the SDTV camera, it is small wonder that 60 to 70 percent of studio camera sales in year 2003 are HDTV cameras (even though many are used only for their downconverted output). This trend, coupled with vigorous competition in the HD camera arena, is achieving an important economy of scale that, in turn, is further driving down the costs of HD cameras.
THE NEED FOR MULTIFORMAT
The quite extraordinary turn of events in the long and arduous North American quest for DTV production and transmission standards -which produced two HDTV standards and a number of SDTV standards-have had a profound effect on the architecture of the contemporary studio camera. Today, of necessity, that has become a multiformat camera. Camera manufacturers quickly recognized that the size of the total studio camera marketplace could simply never sustain separate cameras for each and every digital format. The only rational solution was to mobilize the most contemporary of digital processing to develop cameras capable of switching between all formats. Thus, today, there are studio cameras capable of originating both of the 1920(H) x 1080(V) and the 1280(H) x 720(V) high-definition formats, while also deriving an SDTV 720(H) x 480(V) output. Different technological approaches have been adopted to realize this format nimbleness in picture origination.
The fact that HDTV has now become a broader global agenda has extended the multiformat camera to be additionally dexterous in picture capture rates. All variants of 50 Hz and 60 Hz-including progressive and interlaced-scanning-are widely implemented. Somewhat unexpectedly, digital cinematography surfaced in 1998 as a major new digital HD initiative. And suddenly, the traditional video industry found itself also embracing a picture capture rate that perhaps it had never before properly understood-24 frames per second. Digital 24P-as it is affectionately dubbed-has swept into primetime television production-and is also originating major movies.
Twenty years has indeed borne witness to astounding developments in the high-end studio camera. Life was so simple in 1983. But, the stunning picture quality of today surely portends an unstoppable future dynamic in studio camera development. There is no going back.