Modern Classic SLRs Series :
Canon T-90 - Its computer processing power

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High tech cameras also means they are heavily dependent on the raw computer power to perform their various functions, controls and processing vast amount of data. The T90 has a pair of electronic brains (A circuit of 130,000 thinking elements means 121 items of input data are processed instantaneously: The Electronic Input Dial Control 121 Input Items).

Note: PLEASE USE the MAIN MAP for the viewfinder and LCD display for cross reference in this site. Another page is also equally helpful for its layout of controls and buttons. Two views of the SPC that handle the TTL flash at the mirror box. - Tom Scott -

The T90 has NO mechanical shutter to operate as a back up - just like the AE-1, AE-1 Program or A-1 models. In fact, none of the T series models has a mechanical lever to operate, meaning it will just fall dead when your battery runs out of power. This may seems very uncomfortable to deal with for purist or when you are on a important assignment, but Canon has a large following worldwide and of course, now everyone has accepted the fact that full automation is part of the 'game' in modern photography. How does all of these enormous amount of users' input be simplified ?

The Electronic Input Dial leads to the development of Command Input Dial. Change the way how we handle and operate a modern camera.

Nothing symbolizes the innovative nature of the T90 better than its original Electronic Input Dial. It's the optimum solution to what previously had been a seemingly insolvable problem: how to easily control a vast amount of input data. The design practically changes the way of how the users handle his/her photographic tools - such engineering was influential enough to become trend setting, to be followed and copied by Canon's competitors! Of cause, the T90's original input dial was still at its infancy and conceptual stage during its debut. But its ease-of-use and capabilities eventually leads to further development and upgraded into the more advanced version as used on every Canon AF model currently available on the market. Conventional electronic cameras used various forms of pushbuttons or slide switches, or a combination of the two, for digital data input. Although these systems do get the job done, they are clumsy and don't satisfy some of the photographers who prefer to think in mechanical "analogue" terms, and prefers to use the traditional aperture ring and shutter speed dials. The T90 combines the best of both worlds. The Electronic Input Dial is obviously faster than previous information control systems. It easily handles the vastly increased amount of data that modern electronics generates, like the half-step increments between shutter speeds and aperture settings, for example. Yet it also retains the mechanical "feel" of a rotating ring. When setting the shutter speed, for example, to the right is a faster speed and to the left is a slower one. You quickly get used to it. And there's no need to take your eye off the scene you are photographing.

Conventional way of input may have to give way... I expect Nikon's new AF after the F5 to follow suit and it did, with the Nikon F100.

With the Electronic Input Dial, you can easily control a rather astonishing amount of input data: The T90 has 10 shooting modes, 36 shutter speeds, 20 aperture values, 3 metering modes, 31 manual film speed settings, 12 exposure compensation settings and 9 multiple exposure frames. Yet the dial is so naturally easy to operate that you quickly forget just how sophisticated the system is.

The main "brain" of the T90 for all these calculations, where its micro circuitry features 6 LSIs, 4 ICs, and a quartz oscillator (refer to illustrations above, at top of the page). The core of this system is a dual CPU (Central Processing Unit) configuration. The main CPU handles overall sequence control and operates at low power, while the sub CPU, directed by the main CPU, runs at a much higher clock speed - 1 MHz for the sub-CPU as compared to the "slower" 32 kHz of the main processing unit. This twin-brain system allows the T90 to process a vast amount of input information in lightning-fast real time operation. The two CPUs keep in touch by means of a high-speed serial digital UO interface LSI. The whole circuit maintains a volume of about 130,000 elements - about 30 times more than the Canon A-1, and approximately 7.5 times more than the Canon T70. The main CPU handles the LCD panel and operation sequence control for the entire camera. The sub CPU is in charge of information display inside the view finder, algorithm calculation plus memory after metering, and high-speed data processing for sequence control operations concerning the 3-motor system.

Concept | Capabilities

Its Metering, Exposure control, Flash photography, Viewfinder display, Film Backs, Built-in Motor Drive, the brains, Focusing Screens Other capabilities and the eyes of Canon; Full specifications with details illustrations of its various controls, available in HTML / PDF (184K) format.

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Maintenance Team: Credit: Pawel Nabe for his image on the Data Memory Back. EEwyn Foo, my nephew, who has spent quite a number of nights converting the original manual in HTML format. Mr. Richard Yeow, General Manager -Optical Division of Canon Marketing for granting special permission to reproduce this manual into HTML format in his site as a form of obligation to all the T90 users worldwide. Maintainders of the T90 Message Board: Kaipin, Terry Carraway & Dr Strangelove; Tom Scott, for his images of the SPD cell, Chris Tutti for his initial effort to scan and prepared the T90 manual in PDF format. My staffs Miss Wati and Mirza for helping the basic setup work. * Canon, T90, FD Lenses, Canon Marketing are registered trade names or trademarks of Canon Inc. Japan.