This Topic will focus on digital sensors, which are at the heart of modern cameras, by following the path of image formation. It will show the benefits and limitations of digital photography technology and help decipher the true meaning of the announcements made by manufacturers about the performance of their devices.
From camcorders to digital photography, here is the story, probably incomplete, of the first cameras.
It is possible to draw a parallel between the evolution of camcorders and that of digital cameras. Indeed, it is obvious that the two types of devices have in common the same type of photosensitive sensor to form the image.
However, the technical constraints being quite different, their evolution did not follow the same path initially. Camcorders had a much earlier popular success than digital cameras (APN), although the first cameras of these two categories appeared during the same period. In both cases, the pioneer was Sony
Camcorders and cameras (the Mavica, from Sony)
Indeed, the television image had a much lower definition than what is necessary to have a good photograph. The vertical definition was 625 lines (in the European standard) but the VHS VCRs had a bandwidth such that the effective definition was less than 300 lines. The eye tolerates a limited definition for a moving image more easily than for a still image. For this reason, it was easier to produce good sensors for camcorders than for cameras.
Another constraint was the analog technology of television (and therefore video recorders). For a long time, camcorders recorded images in an analog format. On the contrary, cameras had to choose the digital option from the outset to allow an easily usable recording format.
The first camcorder was marketed in 1983 by Sony under the name of Betamovie (in the late Betamax format). Then, in 1985, appeared the first VHS camcorder, created by JVC. Sony, in association with various other manufacturers, responded by introducing the same year the video recording medium 8 based on a much smaller cassette containing an 8 mm wide band. On the other hand, since these cassettes cannot be played in a living room VCR, the camcorder had to connect to the TV. These formats then underwent various evolutions (the video format 8 evolving in HI-8 and the VHS in VHS-C), but it was not until 1996 that Sony commercialized the first amateur digital camcorder. It used the same cassette as the HI-8.
The first digital camera appears to have been marketed in 1981. It was Sony’s Mavica, a reflex camera with 279,300 pixels and recording 50 images on a mini-floppy disk. It cost 650 dollars and its floppy disk drive 220 dollars. It was used by press photographers for the Olympic Games in Los Angeles.
Kodak and the first professional cameras
It was not until 1990 that Kodak released the first professional cameras. Logitech embarked on the adventure in 1992, followed by Apple in 1994. The definition, still mediocre, was in the order of 0.3 megapixel. The first LCD back seems to have equipped a Casio model in 1995.
For the record, the JPEG image format was officially defined in 1991 and its standard definitively adopted in 1992. We can see why digital photography for the public started later than camcorders.
It was not until 1999 that definitions greater than 1 megapixel began to spread. The entire start-up period is dominated by compact cameras, intended for the general public, because of the limited definition of the digital image which did not allow for strong enlargements. These devices are currently the best-selling because of their small footprint and the almost playful ease of use.
The first consumer reflex cameras: the EOS D30, by Canon
However, in 2000, Canon released the first SLR for the public, the EOS D30 with 3.2 million pixels on a CMOS sensor manufactured by Canon, preceded in 1987 by an EOS 650 with a more confidential Kodak diffusion sensor.
Various well-known brands have since taken over the SLR market, although two of them dominate the market. Their definition is of the order of 10 to 20 megapixels but can go up to 50 megapixels for particularly expensive models. The compacts currently have a definition that can go up to 20 megapixels, joining that of excellent reflex cameras.
It is obvious that the most important element of all these devices is the sensor. Knowledge of its characteristics makes it possible to understand its limitations, and consequently, some pitfalls to avoid. However, this sensor would be nothing without the processor that transforms electrical signals into a visible image on the screen that can be pulled on paper. This dossier will therefore focus on the sensor and the formation of the image.
The sensors differ in size, technology and, of course, in the number of pixels that make up the image.
2. It is impossible to speak of digital photography without mentioning marks. This does not imply publicity, nor, on the contrary, criticism for these companies.