Three decades ago in March 1987, the very first EOS model, EOS 650, was released. EOS is the acronym for “Electro-Optical System”. It is also the name of the Goddess of Dawn in Greek mythology. Adopting a fully-electronic mount, the EOS series aimed to become a pioneer that ushered in a new era for SLR cameras. In commemoration of the 30th anniversary of the birth of EOS, this is the first in a series of three articles that trace the evolution of EOS, starting from the release of the first EOS model to its transformation from an SLR into a digital SLR system, before rounding up with an introduction of the ever-evolving EOS technology.
EOS 650 (Released in 1987)
The EOS 650 is the first camera that was released under the EOS series. AF sensors, microcomputers and other latest technologies of the time were introduced to achieve AF with a high level of precision. The fully-electronic EF mount that was also first adopted back then is still being used 30 years later on the EOS cameras today.
EOS 650 – The unrivalled model among all AF SLR cameras
Boasting enhanced AF accuracy, better operability and more accurate metering and exposure control as well as a fully-electronic mount, the EOS 650 was packed with the latest technologies of the time in anticipation of the trends and needs 30 years ahead. Technologies developed by Canon, such as the BASIS focusing sensor and the high-precision AF contributed by the microcomputer, were unrivalled compared to the performance of other competing SLR cameras with AF capabilities.
In terms of design, efforts were also made to deliver a more pleasant photography experience. Unlike the linear design of conventional SLR cameras back then, a curved style was adopted to enhance the ergonomics of the camera, including a larger grip for a firmer hold, and a Main Dial as well as the layout around the shutter button with the placement of fingers taken into consideration.
The design concept of EOS, which is to introduce cutting-edge technologies to achieve the ideal camera without being constrained by conventional wisdom, is still adopted by the models today 30 years later. This is one of the reasons why EOS cameras have long been the choice of users worldwide.
Catalogues from 30 years ago (EOS 650 (left), EOS 650 & 620 (right))
Two months after the release of the EOS 650 in March 1987, Canon launched another high-end model, the EOS 620. The first EOS camera was not designed to be a flagship model. Instead, the aim was to produce a reasonably-priced standard model that was packed with high-spec features by incorporating the latest element technologies.
The EOS series, which started with the release of the EOS 650, marked its 30th anniversary in March 2017. The three core principles for the development of EOS have been passed down and remain essential today.
3 Principles for EOS Development:
1. Renewal of the AF mechanism must not be used as a reason for pricing the EOS cameras at a much higher level than that of existing cameras.
2. The EOS camera must be capable of AF tracking with a 300mm f/2.8 lens when taking handheld photos of indoor sports.
3. The AF sensitivity must be equivalent to the brightness level of the metering sensitivity.
Lens drive technology for achieving speed and comfort
Starting from the EOS 650, a newly-developed EF mount was adopted for the EOS series. EF, which stands for “Electro Focus”, represents Canon’s approach that places electronic focusing technology at the fore. AF cameras at that time had a tab between the camera body and the lens for controlling the lens aperture blades. However, by introducing a built-in EMD (Electro-magnetic Diaphragm) in the lens for controlling the aperture blades electronically, Canon succeeded in eliminating the mechanical linkage between the body and the lens, thus achieving a fully-electronic EF mount. Three decades later, the fully-electronic mount continues to maintain its compatibility and provides the foundation for the introduction of the latest technologies.
Lens mount on the EOS camera body
Lens mount on the EF lens body
The latest EF lens functions smoothly when it is mounted to the EOS 650, the first EOS camera. Similarly, the first-generation EF lens is also fully compatible with the latest EOS camera. Communication of electronic signals is done through the terminal contacts on the EOS camera body (left photo) and EF lens (right photo). Not only does the adoption of a fully-electronic mount eliminates the need for mechanical linkage, it has also allowed for complete mutual compatibility between all cameras and lenses that support this feature.
Through communication of electronic signals via the terminal contacts, the EF mount transmits information of the lens to the camera upon receiving a request from the camera, and the camera controls the lens based on the information received. The IS (Image Stabilizer), which cancels any camera shake by moving the IS unit in the lens, and the USM motor, which establishes focus quickly and smoothly through ultrasonic vibrations according to the AF metering information of the camera, are examples of lens technologies that can only be made possible when there is communication in both directions between the camera and the lens.
With the built-in EMD (Electro-magnetic Diaphragm), which is an actuator for aperture drive control, the aperture is driven electromagnetically using the deformation stepping motor and aperture blade unit.
Canon’s EF lenses are equipped with a wide variety of lens drive technologies, such as the USM lens that establishes focus quickly and smoothly, and the IS (Image Stabilizer) that suppresses camera shake.
EF mount diameter designed to achieve f/1.0
17 EF lenses were released in conjunction with the launch of the EOS 650, one of which was the EF 50mm f/1.0L USM, a lens that was infused with the enthusiasm of Canon engineers who were part of the EOS development process. During the discussion to determine the specifications for the EF mount diameter and flangeback distance, engineers who were designers of the optics strongly requested that dimensions capable of achieving f/1.0 be adopted for the lens.
EF50mm f/1.0L USM (Released in 1989)
Weighing 985g with a lens construction of 11 elements in 9 groups, closest focusing distance of 60cm and filter diameter of 72mm, this standard lens had the largest diameter in the world at the time it was released.
At that time, Canon’s engineers were planning to create a dream lens once again if they were to revamp the mount. This was because Canon had, in the past, successfully commercialised a 50mm f/0.95 lens for the Canon 7 rangefinder (released in 1961). Due to physical constraints such as the mount diameter of the FD mount, which was employed prior to the birth of the EF mount, it was not possible to create an f/1.0 interchangeable lens. To make a 50mm f/1.0 lens, a mount diameter of approximately 50mm was indispensable considering the ratio of the diameter to the flangeback distance. The flangeback distance of the EF mount was 44mm while the diameter was 54mm, which met the requirement for achieving a 50mm f/1.0 lens.
The Canon 7 (Released in 1961)
The Canon 7, which provided the basic concept for the development of the 50mm f/0.95 lens, was launched at the 7th Photokina (1960). Until today (2017), the f/0.95 lens still remains the brightest lens.
This large-diameter mount also offers many advantages in the digital era, such as allowing the camera to produce images that make effective use of the overwhelmingly shallow depth of field, enabling photography under low-light conditions, development of a bright optical viewfinder and reduction of diffraction. This is probably one of the rare cases where the emphasis on keeping tradition has helped to pave the future of EOS.
Moving forward, the advanced AF system of the EOS will revolutionise the future shooting style of professional photographers. In the next two articles, we will introduce the background to the EOS as a leader in the camera industry after its rebirth as a digital SLR system.
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