The adoption of larger sensors for broadcast camerawork has a telling historic parallel in the gold rush of 1950s cinema. At a time when the cinema industry was increasingly concerned by competition from home television, there was huge interest in making the movie theater experience more spectacular.  In some ways, the status quo in 2025 represents almost an inversion of that, with television reaching for the techniques of mid-century theatrical exhibition in the interests of attracting eyeballs.

In pursuit of that, broadcasters have sought larger sensors, and those sensors have often been described in terms of the motion picture film formats they approximate. By far the most common format for larger-sensor cameras is commonly called Super 35, from the 35mm motion picture film standard which had existed since the late 19th century. At the time the format was developed, George Eastman’s company was selling film in 70mm wide rolls, and it is enticing to assume that Thomas Edison’s lab simply divided it in two to reach the familiar 35mm dimension.

The Genesis Of Sensor Size

The reality was not quite that simple. The man most responsible for the world’s adoption of a 35mm wide film strip was Edison collaborator William Kennedy Laurie Dickson. While working on the physical layout, Dickson picked his dimensions according to the need for enough film area to form an acceptably sharp image on the film stocks of the time, and arrived at a frame one inch wide. Dickson added three-eighths of an inch to allow for sprocket holes, resulting in film that was 1-⅜”, or 34.925mm, across. The height of the frame was calculated to create an image three quarters as tall as it was wide, another Dickson choice. This meant four sprocket holes per frame, a number that did not change even when the frame was later cropped to fill a wider screen.

The precise numbers would later be revised, repeatedly, by several different standardization efforts. To this day, sensors described as “Super 35” are often somewhat variable in precise dimensions, which is mostly not very important. The fundamental choices, though, last to this day - although by the 1950s, film studios were searching for more visual spectacle to tempt audiences away from television and back into theaters. That drive provoked the development of formats which rejoiced in names which could only be dreamt of in a utopian mid-century context: VistaVision, Cinerama and CinemaScope.

These approaches inflated budgets in comparison to conventional cinematography, using more film or awkward, expensive lenses. Then, in 1954, the SuperScope corporation was founded. One of SuperScope’s ideas was deceptively simple: to make idle soundtrack space available for picture. Given the existence of sprocket holes, no 35mm format has ever created an image which is actually 35mm wide, but before the dawn of sound, silent films used almost all of the space between sprocket holes for their images. Reserving space for an optical soundtrack made the image narrower. Even though motion picture film cameras did not record sound, space for it was still reserved on the negative.

SuperScope simply proposed using all of the available area for picture - almost a return to the pre-sound approach. The resulting negative could not be directly transferred to a 35mm release print which would need optical sound, so it required an optical reduction (or, much later, digital scanning and laser film recording). Even so, it achieved a sharper, finer-grained image while using no additional film, and the approach remains popular to this day. The mostly synonymous term Super 35 arose later, echoing Super 16 and Super 8, both of which seek to use the maximum possible area of the film for picture.

Cinema’s postwar creative streak provoked a lot of new format ideas, some of which have also found a home in the modern imagination. The format we call “full frame” is notionally based on a still photography frame eight sprocket holes wide, but is broadly similar to the historic format called VistaVision. Cinema camera manufacturers have released designs with “65” in the title, recalling the 65mm film used to originate 70mm releases, all of which might find use on sufficiently adventurous broadcast projects.

The Dawn Of Electronic Sensors

As broadcast explores large-sensor cameras, then, it has been borrowing from a long history of designs which grew from situations and technologies which have little to do with modern broadcasting. Perhaps we should not be surprised to discover that the current crop of broadcast cameras use configurations of sensors and lenses which derive from almost as convoluted a background.

The technical specifics of Philo Farnsworth’s early experiments with image dissector tubes vary, but many of his tube designs were around four inches in diameter. The glass picture tubes widely used in mid-century cameras used different technology, but were often around the same size. RCA’s documentation for its model 7295-A, an early-60s era Image Orthicon tube, show that it was 4.5” in diameter. The company specifies a 1.6” image diagonal. That makes the active area considerably larger than a Super 35 frame, and so large-sensor camerawork for television is more or less as old as television.

Those numbers also tell us something about the way in which sensor sizes are described for broadcast cameras. Cameras of that era were often described in terms of their tube diameter - four and a half inches, in that case. These large tubes made for big, heavy cameras with compromised portability. With the introduction of color imaging, cameras required three (or, exceptionally, four) tubes, creating a powerful drive toward miniaturization.

RCA’s famous TK-40 cameras, for instance, weighed some 300 pounds for the camera head alone. Through the 50s - just as the cinema world was becoming nervous about television - tube sizes were already shrinking, with one-inch tubes common by the 60s.

Today’s terminology often describes broadcast cameras as ⅔”. Again, no part of the active image on a ⅔” camera is actually two thirds of an inch across. The value refers to the diameter of the tube, not the size of the active sensitive area. At a mere 9.6mm across, the effective sensor size in a classical camera with ⅔” tubes area is far smaller even than a 16mm film frame.

With the advent of CCD and, then, CMOS technology, broadcast camera sensor sizes could be maintained, allowing the same lenses and operational practices to be used. So, it may not be so much that film frames are large. Rather, after a large-sensor beginning, broadcast cameras have long been a key application of very small sensors.

Outside of live and studio broadcast work, solid-state sensor technology has allowed manufacturers to choose a wide variety of engineering compromises around sensitivity, dynamic range, noise, and the field of view available from different lenses. The desire for fast, high-ratio zoom lenses, and the challenges of focusing a distant subject, have generally conspired to keep sensors for live broadcast reasonably small.

All of this matters because audience expectations about what good pictures look like are mostly informed by life experience, and that life experience arises from all this history. For decades - for the entire life of most people alive today - images made by larger sensors have been more closely associated with glossier, better-funded production. The systems which created that situation were not deliberately designed to have that effect. They were designed around technical expediency. An understanding of how that situation arose can help us understand why the desire for larger imaging sensors is currently so strong.