Canon T90
Although it was overtaken by the autofocus revolution and Canon's new, incompatible EOS (Electro-Optical System) after only a year in production, the T90 pioneered many concepts seen in high-end Canon cameras up to the present day, particularly the user interface, industrial design, and the high level of automation.
Canon considered Colani's contribution important enough to present him with the first production T90 body, engraved with his name.
Computer-aided design techniques were introduced to Canon for the T90, as well as the use of computer controlled (CNC) milling machines to make the molding dies for the shell.
Much work went into human factors engineering to create an ergonomic user interface for the camera.
A control wheel is located behind the shutter release and convenient for the right index finger is used to adjust most camera settings in conjunction with other buttons located for the right thumb and on the left-hand side of the camera; again, this design is still used in Canon's digital SLRs in current production.
The T90 includes an integral motor driven film advance, focal plane shutter, mirror and aperture cocking and rewind functions.
This is not a user-serviceable part, and when it fails the camera has to be brought to a service center where the battery can be replaced by a Canon technician.
These adjust the camera's metering decisions to ensure extremes of tonal range are not muted and grey in the final exposure.
Center-weighted and partial area metering are performed by a double-area silicon photocell (SPC) in Canon's standard location above the eyepiece, while spot metering is performed by another SPC located at the bottom of the mirror box.
Program AE (Auto-Exposure) mode puts exposure control completely in the hands of the camera.
In either of the latter two modes, a Safety Shift feature allows the camera to adjust the "fixed" parameter if it can not obtain a correct exposure otherwise.
Safety Shift lets the camera reduce the aperture until it can achieve a correct exposure at maximum shutter speed.
The Safety Shift feature can be turned on and off by pressing two buttons on the back of the camera near the base.
In this mode, the pre-flash is used in conjunction with spot metering to determine the correct exposure in advance of taking the picture.
This supports TTL and manual models only, and contains two flash tubes, one on either side, which can be fired separately or together.
The system consists of the flash ring itself, which fits onto the end of the lens, and a control unit that screws into the hot shoe atop the camera.
The subsequent difficulty in obtaining repair services is likely to discourage any remaining professional use of these cameras.
LCD displays age and wear out at a varying rate dependent on environmental conditions, use and other factors.
Commonly quoted lifespans are about five to ten years;[3] thus, many T90s will have displays nearing the end of their lives, even if they have been replaced.
Another common problem is failure of the second internal battery that retains frame number/ISO settings, replacement of which requires service by a person skilled in soldering techniques and camera disassembly.
But if left unused for an extended period of time the circuit will need to be replaced, an expensive and time-consuming proposition.
A good short-term solution is to lightly clean the shutter diaphragm with a cotton ball and lighter fluid.
As with some other electronically controlled SLR film cameras, a working Canon T90 can be a bargain on the used market.
