In Place of Film

by John Henshall

Electronic cameras have been with us since the beginnings of television 55 years ago. John Henshall traces their evolution, looks at how they work, and examines today's high resolution cameras, like the one which captured this high quality image.

Without imaging there can be no photography.

Without a digital camera, there is no such thing as digital imaging. Unfortunately, no cameras actually make a digital image: they must all be converted from analogue to digital either inside or outside the camera. Strictly speaking, therefore, digital imaging is a misnomer.

Imagine how revolutionary the concept of electronic photography would have seemed way back in Edwardian times.

This was the mechanical age, when fathers took home Edison cylinder phonographs to the great excitement of their incredulous families. The automobile was a rare sight on the roads. Cinema was in its silent infancy. Louis Blériot made his historic flight over the English Channel, bringing manned flight to England for the first time in 1909.

Yet, incredibly, a purely electronic system of photography had been proposed a year earlier, in the very year in which Henry Ford introduced his Model T.

Pie in the sky? Science fiction?

Though there were many complex practical aspects which prevented the process from becoming an immediate practicality, astonishingly, it took only a quarter of a century for the proposal to become fact, as the world's first system of electronic photography was born.

The camera was completely electronic, producing pictures without any mechanical assistance, apart from focusing. The system even enabled pictures to be sent from place to place along a wire. Most amazingly of all, using invisible waves, pictures could be sent through the ether. As though all this was not enough, the process produced twenty five pictures every second, accompanied by synchronised sound.

Developed and refined since its inception in London just over fifty five years ago, the system, which has been in daily use ever since 1936, is still basically the same as that proposed in 1908 by Alan Archibald Campbell Swinton FRS.

Mark Twain once defined a crank as "a man with a new idea - until it catches on". Despite those who scoffed at Campbell Swinton's ideas, his lateral thought and imagination paid off. Looking back, his ideas now seem rather "obvious" but, in Edwardian Britain, many considered them eccentric.

Campbell Swinton's system came to be called television. We now take it so much for granted that it is easy to forget that this was the first workable system of purely electronic photography.

Compared with his ideas, the changes in photography, printing and publishing today seem quite humdrum.

In 1932, EMI engineers W F Tedham and J D McGee turned Campbell Swinton's dream into reality by producing the first electronic picture pick-up tube in secret experiments, contrary to the orders of their bosses at EMI. They displayed their images on a cathode ray tube.

Then, only four years later, the world's first authentic electronic television service opened at the BBC studios at Alexandra Palace, in north London in 1936. The system was so good that it ousted Baird's mechanical system in the following year.

The era of electronic imaging had begun.

Development then slowed down. True, television as a means of communication has blossomed. But, apart from the addition of colour and an increase in the number of scanning lines, television has hardly changed since its inception. It remains, essentially as Campbell Swinton visualised it, eighty five years ago. Some vision!


It is now over twelve years since Sony shook the photographic world by launching MAVICA, the first MAgnetic VIdeo CAmera, a stills camera which does not use any film.

The appearance of Mavica stirred imaginations like science fiction coming true, signalling the advent of a new basis for stills photography, the most profound change to photographic methods since William Henry Fox Talbot. When we are able to look back from the future age of electronic photography it may be that this will prove to be Sony's most significant electronic innovation, a "giant leap" for imaging.

Sony make a wide range of television cameras, from amateur camcorders, through industrial and professional, to full broadcast specification. Beyond normal broadcast, they produce the HDC-500 high definition television camera, which makes the most stunning 1125-line pictures ever seen. With a product range which spans the entire spectrum of usage, they are world leaders in television camera design.

In many ways, Mavica is just another Sony television camera, for the pictures it produces are television pictures. But instead of twenty five pictures per second (in Europe) or thirty (in Japan and the USA), this camera produces single frames of video. This is a still video camera. "Still video" is almost a contradiction in terms: the camera produces video pictures which, a frame at a time, are still pictures.

In place of film, Mavica records still video images on a two inch floppy disk - looking just like a miniature computer disk - which slots into the camera. A common misconception is that the recordings on these disks are digital, as on the larger floppies used in computers. In fact still video cameras produce and record a conventional analogue video signal.

What made still video possible was the coming of a solid state imaging device called a CCD, the initials of the phrase "Charge Coupled Device". A CCD is a light-sensitive integrated circuit. Place one in the image plane, where the film would normally go, and it converts the light energy which falls onto it into a train of electrical energy called a video signal.

"Da Vinci". Amateur camera advertised on American Airlines 1993. As many prints as you want from the shot you have just taken. No storage memory. Thermal paper.

Mavica showed not only that a system of electronic video stills photography was viable but also practicable. Most importantly, it made film manufacturers realise that the future world of imaging would not be coated with silver.

CCD chips, in their infancy when the first Mavica was launched, developed rapidly for use in broadcast television cameras. Today, CCDs have completely ousted camera tubes from domestic, industrial and broadcast television cameras.

Although Mavica cameras are marketed in Japan and America, Sony have never produced a 625-line PAL camera for the European market. They left that honour to Canon, who introduced their 625-line PAL Ion RC-251 still video camera through high street stores. The problem was that it was a rather expensive electronic toy, from which it was expensive to produce prints. About all you could do with it was view still video shots on a television monitor.

Companies such as John Blishen and Company have found useful markets for Canon still video cameras with UK newspapers such as London's Evening Standard. Blishens have also converted Autotrader from Polaroid to electronic, for its secondhand car advertisements, selling them 360 Canon still video cameras . Apart from these uses, Sony's original system of still video is now obsolescent, the image quality obtainable from still video not being good enough for anything but small reproduction.


Although television was the first system of electronic imaging, one thing that television has always lacked is tangibility. The television image lasts only as long as the persistence of the cathode ray tube on which it is displayed. In my years at the BBC, those facts set me thinking about the future of photography, a future with just one camera, suitable for both still and moving images. The "CameraOne" concept camera was born out of these thoughts in 1978 to illustrate a lecture, and was followed by "HandiCam" in 1984 - predating Sony's use of the name "Handycam" for its consumer camcorders.

In the future, the camera's lens will be an electronic zoom, with no moving parts. Zooming will be accomplished by varying the sensor's scanned area, giving angles of view from 1° to 180°. Iris diaphragm and lens hood functions will be by electronic darkening of the edges of the lens elements. The sensor will be of "photon dimension" for incredible resolution.

Already, some of the features of CameraOne and HandiCam are beginning to become reality. Hybrid mechanical and optical zoom lenses have begun to appear. Compare the HandiCam viewfinder with an Apple Macintosh PowerBook screen: very similar, though HandiCam's picture stretches right to the edge of the screen and predates the PowerBook by eight years! These ideas and many others form part of an outline specification, A Camera for the Twenty First Century.


All filmless cameras today produce images on CCD chips, which are monochrome analogue devices. What is the difference between analogue and digital? How do we have digital colour pictures?

The difference between analogue and digital is similar to the difference between a slope and a flight of stairs.

In a CCD, the electrical charge produced is directly proportional to the light which falls upon the device. The level of charge can be nil, corresponding to black, through to the maximum, corresponding to white, with an infinite number of possibilities in between. To process this information in a computer, it has to be "sampled" digitally. Using the analogy of the slope and stairs, this process is like cutting steps into the slope. You can be anywhere at all on a slope, but only on one precise step of a staircase at a time. This makes it easy to define precisely where you are.

It has been found that two hundred and fifty six steps, from black to white, produce a digital image in which the tonal steps are so close together that the effect, when the image is viewed, is one of continuous tone.

Fine, you might say, but we want colour.

Colour is obtained by analyzing the image in terms of its red, green and blue content, through coloured filters. Multiply the 256 possible levels of red by the 256 possible levels of green and by the 256 possible levels of blue and you get a staggering 16,777,216 possible colour combinations. Just don't ask me to name them all.


Colour analysis in electronic cameras may be made in a number of ways.

It may be achieved by having three CCDs and an optical beam splitter to divide the light into its primary colours. Broadcast television cameras use this method, as does the Sony SEPS-1000 digital camera. It allows "instantaneous" photographs to be imaged but triples the electronics, resulting in a larger, more complex camera.

Sony SEPS - 1000 digital portrait camera

Alternatively, the camera may have one CCD which is exposed three times, in sequence through red, green and blue filters. Arca Swiss and Leaf cameras are among those which use this method. Like the optical beam splitter method, this gives red, green and blue analysis of each point in the image. The quality can be very hight but with a real disadvantage: neither subject nor camera can move between the three exposures. This makes these cameras suitable only for still life subjects.

The Arca Swiss produces extraordinarily good pictures from a television sized CCD sensor. Colours are pure and grain free. Its Arca view camera movements make it a precision instrument.

Arca Swiss digital camera with 15mm Nikon lens.

The Leaf Digital camera is a back containing a huge 30mm square CCD and is available for cameras such as Hasselblad, Mamiya and Sinar. This camera produces 65,536 levels for each colour, from which the required 256 may be chosen. This gives it a long range, in excess of film.

The Leaf Digital Camera Back showing the 3 x 3cm chip.

The Leaf Digital Camera System - fitting to the Back to the Mamiya RZ67.

A third method of colour analysis involves a system of microscopic filters in front of individual pixels of the CCD. The colour is obtained by computer interpolation of the colours of adjacent pixels: if adjacent red, green and blue pixels all return the same signal value, then they are all made grey. If red returns maximum signal while green and blue return nil, then they are all made red. Kodak's Digital Camera systems (DCS100 and DCS200) use this technique. The disadvantage is that the interpolation of colour is not infallible and this can result in coloured ailiasing, "the jaggies", showing on some elements in the picture. The major advantage is that only one exposure is required.


It came as something of a surprise when, in 1991, Kodak introduced the first camera with internal conversion from analogue at the CCD to direct digital output: the Kodak Digital Camera System or DCS. Maybe they were spurred on by the threat - some would call it a promise - to the future of photography which Sony's Mavica heralded but the DCS was, and is, a superb instrument.

Cleverly based on a Nikon F3 body - a favourite among photo-journalists - the camera is connected by an umbilical to a Digital Storage Unit - a box containing a 200 megabyte hard disc on which up to 160 images can be recorded. A small black and white monitor screen on the DSU enables exposure and composition to be checked immediately after each exposure.

A year later, Kodak introduced the DCS200, a completely self-contained camera based on the Nikon 8008/801 camera body, having the ability to record 50 images on an internal 80 megabyte hard disc. This camera is about the same weight as a single lens reflex camera with motordrive. Already the size, weight and convenience of electronic cameras rivals that of their film counterparts.

The real breakthrough in digital imaging will happen when every household owns one. Although the Canon Ion was too early to capture the public imagination, other indications bring that day closer.

The summer 1993 American Airlines in flight magazine contains an advertisement for a digital camera with a built-in printer which can make as many identical prints as the user wishes from the last picture taken, using thermal paper. The camera is for snapshots: it cannot store the images for later use.

Apple Computer are said to be working with Eastman Kodak on two new cameras. Codenamed Mars and Venus, they will combine Apple's reputation for pictures on computers with the experience Kodak has gained with its professional digital cameras.

If they get it right, this could be a winning combination which brings digital images to every desktop, both professional and domestic. So far as digital imaging is concerned, we really aint seen nothing yet.

This review first appeared in "EDI Review" November 1993
This document is Copyright © 1996 John Henshall. All rights reserved.
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