Big Chip Cameras For Broadcast: Even Bigger Chips, Even Higher Resolutions

Audience expectations are evolving beyond traditional cinema aesthetics, and while large-sensor cameras have proven their staying power the future may be more about flexibility rather than absolute sensor size.

All 12 articles in this series are now available in our free eBook ‘Big Chip Cameras For Broadcast’ – download it HERE.

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There is little doubt that large sensor cameras have recently enjoyed an upswell of support among broadcasters looking to raise their game. Anyone planning an investment on the scale of an outside broadcast truck, though, will reasonably ask what the longer-term prospects are.

There is every reason for cinema camera manufacturers to talk up a market which buys a dozen cameras per truck as opposed to the half-dozen owned by a cinema-oriented rental facility. Even so, big chips in broadcast do come with caveats, and enthusiasm for the look of the resulting pictures is a matter of creative intent which is infamously variable.

To be fair, the idea has already shown some endurance. Broadcasters have been enthusiastic about the idea of taking cinema-sized chips to cover live events for at least ten years, with some popularity for studio recording work even before that. Meanwhile, manufacturers have been building purpose-built cameras around purpose-built sensors for almost as long.

That suggests a reasonable level of confidence, although one almost universally-held view is that not every camera on every production can possibly use a large sensor. The problem is no longer technical or financial; a huge range of manufacturers offer inexpensive consumer products with big chips and lots of performance. Caution arises from the practicality of cameras with reduced depth of field and zoom lens capability.

The Real Future

A broadcast might achieve its large sensor results in any one of several ways – with an accessorized cinema camera, with a small and inexpensive transitional stills or production camera, or with a dedicated large-sensor design made just for live work. That distinction might soften as very high resolution sensors make switchable large- and small-sensor modes, even during a single broadcast. That would require a Super-35mm sensor with enough sheer performance to resolve a quality 4K image from the central ⅔”-sized region. Manufacturers have offered cameras with Super-35mm sensors ten or twelve thousand pixels across which might satisfy that need.

Improved sensor density has other implications, such as the potential for small, ⅔”, single-sensor cameras offering performance competitive with three-sensor designs. The traditional three-chip layout was always a concomitant of the limited available sensor technology, and the required optical block to split the image into red, green and blue components made cameras bulky and expensive, as well as greatly complicating lens design.

A camera with a single small sensor might not be directly compatible with extant ⅔” lenses, which are built to work with three-chip cameras using an optical color splitter. Even where those lenses theoretically project a large enough image to cover the sensor, using them with chips can create problems with pronounced blooming at low apertures. An optical adapter to correct that behavior is simple, lightweight and inexpensive, though, and the option to select effective sensor size on each camera – and perhaps even changing it during a production – would ease decision making.

Big, Bigger, Biggest

Optimizing camera designs and workflows around Super-35mm sized sensors is common, although that choice seems to have been made mostly by default. Super-35mm is far from the largest sensor ever deployed. Given that the larger sensors used for broadcast mostly derive from cinema film formats and cinema film formats can be a lot larger, it is logical to wonder whether broadcast, too, might pursue even larger sensors.

Still photographers use full frame to refer to images using eight perforations of 35mm film, run horizontally, for each frame. A film area around 36 by 24mm is common, although the term VistaVision is sometimes – rather inaccurately – used interchangeably. Originally developed in the 1950s by Paramount, VistaVision was a mid-century initiative to improve motion pictures while using the same film. The VistaVision frame is formally slightly larger than the still photography frame, although both have broadly similar behavior for the sake of comparison.

Beyond that, conventional 65mm film frames, each occupying five perforations of 65mm film negative are wider, but about as tall. Even larger sensors are sometimes called medium format in reference to the mostly-unrelated still photography format (yes, “full frame” is smaller than “medium format”). The largest film frames are recorded using 65mm negative turned sideways, like 35mm VistaVision, with fifteen perforations per frame to create the gigantic 69.6 by 48.5mm format of IMAX.

Digital imaging sensors that size are rare, but there are plenty at the full-frame, medium format and 5-perf 65mm level. Full-frame cinema cameras are already within the scope of things which may be rigged for broadcast work, and they have superb performance. Predictably, though, as sensors get larger and larger, issues around lenses and focus conspire to the point where sheer practicality can be compromised. Ultimately, there is a question about how shallow a depth of field is actually desirable.

Special Applications

Some of the simpler reasons to reach for very high capability cameras go beyond broadcast, into the world of special and visual effects. Wide-angle shots taken from helicopters, for instance, might later be used as a background for a hurtling superhero, and have often been photographed using arrays of cinema cameras. Improving sensor technology has made it increasingly practical to record those plates using a single sensor which may be very large.

The technology has applications in broadcast, pairing high-resolution sensors with wide-angle lenses to create region-of-interest cameras. Selecting an area of the frame electronically is naturally easier than building a pan-and-tilt head for an existing camera, although any serious degree of zoom-in requires a lot of performance from the underlying sensor to avoid visible degradation on the enlarged image.

Applications which might actually use all that sensor performance to create single images include things like theme park rides, where designers increasingly pursue displays sharp and bright enough to fool the eye into perceiving reality. Other than in those very special circumstances, though, applications for cameras (and displays) beyond 8K resolution begin to run into fundamental limitations of usefulness.

Motivations

Interest in large sensor broadcast cameras ultimately derives from audience expectation. Conditioned over decades to associate large sensor image characteristics with classy productions, audiences respond well to large-sensor images – but the reason for that is mostly interpretational, not technical. Cinema and television began deliberately seeking to distinguish themselves from each other decades ago, but it has not been until recently that different media – particularly video games and user-generated content – have begun to exert influence of their own.

The modern media landscape is diverse, with high frame rate, vertical aspect ratio, and variable depth of field – even simulated depth of field in video games. The thinking behind those things may not have much to do with cinema images even if the technical origins of them do. Change in the demand for different kinds of pictures is most likely to arise from changing demands for the content which typically uses those kinds of pictures, something increasingly divorced from the origins of those picture characteristics.

Even so, the idea of big-screen pictures as the gold standard has so far seemed durable. Perhaps the most reassuring capability of new camera technology is not so much its absolute sensor size, but the sheer flexibility of large, high-resolution, high frame rate sensors. Whatever happens, the technology seems likely to be able to handle audience expectations. Production staff are increasingly accustomed to producing material for half a dozen different platforms simultaneously. The future, then, seems to demand not so much absolute performance, but flexibility.

All 12 articles in this series are now available in our free eBook ‘Big Chip Cameras For Broadcast’ – download it HERE.

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