Modern Classic SLRs Series :
Canon New F-1 - The use of electronics in the camera

 
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Unlike the rivaling camera such as Nikon F3 of 1980, Olympus OM series or the Contax RTS II which introduced after the New F-1, all of these high-end SLR bodies depend heavily in electronics. It simplifies a lot of complexity involving with camera's functions and enhance many of its features such as shutter timing accuracy and precise exposure control etc. Unfortunately, most of them only provides a sole mechanical speed to enable the camera remains operational even if there is no battery installed or the power cell(s) totally depleted. Among all these professional camera bodies, the New Canon F-1 and Pentax LX are the only two exception. Both of the cameras are leaning more towards to mechanical mechanism rather than dependent of electronics. Of cause, to meet the demands of today's photographers for a multifunctional, high performance, yet compact body shell, extensive use of electronics has become mandatory.

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This means that numerous electronic components must be incorporated in the camera in the little remaining space not occupied by mechanical components, the optical path and mechanical component positioning requirements.


Incorporating complex electronics in such limited space is a far from simple task. The wiring of inter-component connections is particularly difficult; running complex wiring layouts and then soldering them together is just not possible. To do so would not only be impractical from a production cost standpoint, but the camera would also be unable to withstand mechanical shocks or high humidity. In other words, the camera would be generally un-reliable. Noting electronic signals are vital to the operation of the shutter and aperture-priority AE mechanisms; it is essential that great accuracy be achieved in this electromechanical control system and hence cameras often receive less than gentle treatment, their electronic circuits must be much more reliable than those employed in more stationary equipment. Consequently, interfacing technology has become crucial in the field of camera electronics. Without it, cameras would either have to settle for less than satisfactory electronic performance, or do without electronics altogether. Canon does has its advantage in some proven techniques borrowed from their hugely successful "A" series SLR camera models, of which it has developed and incorporating some of the new interfacing techniques for its New F-1 as well. The picture above may not shown the whole system outlook in the electronic circuitry, but the illustration supplied by Canon Marketing Service Team Members in Malaysia helped a lot. I hope these are helpful for you to understand how it works:

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*Credit: Images and info related to internal circuits of the New F-1 in this page was kindly furnished by Canon Marketing, although it may not benefit many, but certainly would be helpful to some. Some sections were a little commercial, but hope you can digest them, as I need these info to "complete" the site.




Simplification of the New F-1's electronic circuitry was prompted by the development of a new large-scale integrated (LSI) circuit which accommodates the CPU on a single silicon chip. Had conventional LSls been used, the New F-1 would have resulted in a prohibitively large camera body.
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One of the most concerned issue in incorporating electronic circuitry into cameras was humidity and electronic shock. Electronic circuits and components have a notorious reputation for being sensitive to moisture. The Nikon F3 has that upgrade in applying a layer of exposy materials over the main electronic components and the Pentax LX has O-Rings all over at strategic points of entries for possible leakage.


While the New F-1 has their own way as well to protect the camera's electronic circuitry from environmental conditions. The key to this method is a special plastic film called
Permanent Photo polymer Coating. Used to encapsulate the main circuit board and CPU, the film completely protects these sensitive elements from the effects of high humidity and condensation usually caused by rapid temperature changes. And to be extra certain that the camera will keep on working in rain or snow, all electronic components have been hermetically sealed. And to ensure that the New F-1's exposure reading is not affected by temperature changes occurring within the camera, another special thin film semiconductor fabrication techniques which concentrate the resistors on single resistor plates. Since each resistor is constructed from the same material and located on the same single layer within the camera, resistance to temperature changes is much better.

Furthermore, a special technique called laser trimming is used to adjust each resistor to its proper exposure value, thus allowing the resistor plate to be connected to the main circuit board without the need for further adjustments. Special elastic connectors are used to connect the resistor plates and flexible circuit board to the main circuit board without the need for soldering. These highly reliable edge connectors use an encapsulating material of silicon-base epoxy, with the printed circuits of the flexible circuit board joined by extremely accurately dimensioned gold-plated stainless steel wiring. Electrical contact is thus excellent even at high temperatures. An additional advantage is that the covering connector protects the printed circuit from contaminants such as oil and dirt.

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One of the interesting point is the aperture value information resistor plate. Through connecting the lens aperture signal lever to the information plate by means of a high-speed micro brush, this resistor plate controls the lens aperture. Movement along the plate stops when voltage reaches the level indicated by the exposure meter. To test the durability of this process, the resistor plate was subjected to 100,000 strokes from the high-speed microbrush.


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How are these durable resistor plates constructed in the first place, though? First, some precious metals were used, like gold & silver, to assure the contact and wear characteristics is improved. Secondly, fabrication processes were took place in an extremely clean environment. Even microscopic dust particles must not be allowed to contaminate the material. Consequently, the New F-1's resistor plates are fabricated in clean rooms, where the workers wear smocks and masks, and must pass through several "dust-barriers" before entering the rooms. Thus, no expense was spared in assuring the durability and accuracy of the New F-1's photometry system.


Other factors which contribute to the high quality of the New F-1's resistor plates include constructing extremely hard wiping surfaces, polished to a mirror-smooth finish. Also, the electrodes are spaced as closely to one another as interference-free performance allows. And finally, the ceramic micro brushes have been made to ensure good contact and wear characteristics.

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The ASA and shutter speed information resistor plates in the New F-1 are fabricated through a process in which an extremely thin film of precious metal is deposited on the epoxy substrate. This method of printing resistors on the printed circuit boards results in accuracy that could not possibly be duplicated by mechanical means. Each board consists of a foil and resistance layer fabricated onto a printed circuit glass-epoxy board. The proper resistance value is then obtained through photo etching, a process which uses lasers and computer data to reduce the thickness of the layer until the desired resistance is reached.


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After the proper thickness is obtained, the resistor is adjusted to its correct value through laser-trimming. The end effect is complete accuracy, with minimal variations between batches. Moreover, resistor packing is dense, and wear characteristics are superb.


The conventional method of using a rotating brush and stationary information plate has been reversed; the plate is now the rotating element. This means that the resistor plate is not subjected to thermal stress during the soldering process. Furthermore, the electrode pattern faces down in the New F-1, to lessen the chance of electrode shorting, should the camera get wet.

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Many innovations in the New F-1 were truly original and innovative. The use of digital/analog (hybrid) electronic circuitry in the New F-1, earlier experiences with the A-1 (Fully auto) which is an extreme case to the previous F-1, which is a all mechanical body saw the New F-1 encompass the best of both types of circuitry are incorporated to expand functions, reliability, and ease of use. While you can see the exposure meter uses an analog display on the New F-1; on the other hand, all shutter-speed and aperture-related functions in the camera are controlled digitally.


Another thing to note is, since camera has turned to electronics, most of the manufacturers has put a lot of emphasis in energy saving features. It is natural, as camera like the New F-1 (And others) were a leap direct from the all mechanical camera era, features like the
energy-saving, instant-response metering SPC/discharge circuit were built into the shutter button assembly as well. The electromagnetic shutter-release system was also selected for its smooth, light touch operation. To activate the meter, gently press the shutter button, depress it fully, and the shutter is released and mostly, it will turn off automatically in 16 sec to conserve battery power.

Instruction Manual: Canon New F-1 Camera | Motor Drive FN | Canon High Speed Motor Drive Camera |
Main Reference/Layout Map for body: HTML | PDF (471k)
Specifications: HTML | PDF (58k)

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Credit: Mr Richard Yeow, General Manager of camera and video division, Canon Marketing, Malaysia and Tony Kano, for being so supportive and granting permission to use some of the original content of Canon; Mr Philip Chong for patching some mistakes made earlier in this site. Made with a PowerMac, Broadcating with a RedHat Linux Server.