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Electronic Circuits and Power Sources
The electronic circuitry in the EOS-1N comprises a total of 9 LSI and IC groups along with a quartz oscillator, display elements and other circuit components controlled by two CPUs. Input operations, calculations and sequence control processing are carried out using digital signals with the exception of the metering IC and some 1/0 functions. The overall scale of the circuit comprising the camera body, lens and-Power Drive Booster E1 is equivalent to the EOS-1.
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Model(s) / Items
Light emitting elements
Breakdown of Principle Circuit Components:- Autofocusing computations are carried out based on a high-speed 12MHz (12 million cycles/see) reference clock pulse, and overall camera sequence control is carried out based on an 8.38MHz clock pulse.
(2) Twin CPU Configuration The EOS-1N employs a high-speed super microcomputer dedicated to performing AF calculations, and a separate 8-bit CPU for carrying out AE calculations and sequence control, combined in a parallel simultaneous processing twin CPU configuration. This design achieves both faster AF processing speed and improved control precision. The main specifications for the twin CPUs are shown in Table below.
Twin CPUs Specification & Comparison between Canon EOS-1N & EOS-1:-
Canon EOS-1N (16 bits x 5)
Older Canon EOS-1 model
Minimum calculation time
12.0 MHz @ 0.166 ps
Number of instructions
Addition / subtraction / division: @ 32 bit
Addition / subtraction / division: @ 16 bits; Multiplication: 8 bit
Addition / subtraction / division: @ 16 bits; Multiplication: 8 bit
Multiplication: 16 bit
8 bits x 2;16 bits x 2
16 bits x 5
16 bit x 16
16 bit x 4; 8 bits x 4
16 bits x 5
(3) Three (3) Main LSI and IC Functions The devices below outlined various functions and purpose in the camera.
M-CPU Main Central Processing Unit: Receives input data from various input sources such as the electronic input dials and carries out overall camera sequence control including AE-related processing/control and motor control. Also carries out display control via the LCD driver. AF-CPU Auto Focus CPU: An advanced high-speed super-microcomputer dedicated to AF-related processing. Performs data transmission between beeper and EL illumination components. I/O Input/Output Interface: Primarily controlled by the AF-CPU, this 1/0 unit functions as an analog interface to the TTL flash metering sensor, as a digital interface to the flash unit, and as an interface to the lens, camera back and BASIS IC. LCD Driver This LSI always operates and functions as a driver for the external LCD panel and the viewfinder LCD, Also carries out control of the electronic beeper and EL illumination components. Metering sensor This is an LSI made by Canon for carrying out evaluative metering, partial metering and spot metering (via custom function control). It integrates a high-sensitivity sixteen-zone SPC sensor on the same chip with amplifiers for use by the sensor, and is packaged in a clear mold package. This is virtually the same LSI as is used in the EOS 5. Focusing sensor This an LS1 made by Canon which integrates the high-precision multi-BASIS AF focusing sensor (including a central cross-type rangefinding sensor and five focusing points), a fine spot metering sensor and amplifiers all on one chip. It is packaged in a 1-piece mold package. Dial IC IC for detecting input pulses from the quick control dial. Motor Driver- 1 M-1 motor control IC. This IC features a wide operating voltage range of 4V to 15V. Motor Driver-2 "Smart Power"M-2 motor control IC. Motor Driver-3 -PDB-E1 IC for controlling the M-3 motor which carries out high-speed mechanism charging. SW-Lock IC - PDB-E1 IC for controlling the operation/non-operation of the SW-1, SW-2, and AE lock switches located on the Power Drive Booster E1.
(4) Power Sources: -
(a) Main power source,
As AF electronic SLR cameras can consume a lot of power due to its focusing requirement. The bare basic body of the Canon EOS-1N has a removable battery pack which double acts as the hand grip (GR-E1). It can accept a few options in its power supply which includes AC/DC coupled connection. The Canon Battery Pack BP-E1 accepts 4 x AA size cells or lithium cells. For best performance, Canon PDB-E1 can toggle between 2CR5 lithium as well as alkaline batteries and lithium cells. Power sources also affect the performance of the camera in terms of rapid shooting sequence but not other normal camera functions or features.
In order to avoid repetitive resources, also check Various options on Power Sources for Canon EOS-1N as well as Film Transport.
(b) Elimination of backup battery Unlike the earlier EOS-1, the Canon EOS-1N doesn't required a back-up cell inside the camera. Why would the camera requires a memory back-up battery ? With the EOS-1, removing the Power Drive Booster E1 from the camera caused the power to the camera to be cut momentarily. To provide enough time for the camera status information to be stored in the EEPROM, therefore, the camera required a backup battery to protect the operation sequence-related memory contents. With the EOS-1N, however, the sequence memory function performed by the backup battery in the EOS-1 is carried out by a newly-developed microcomputer built into the EEPROM which writes necessary camera operation data into the EEPROM at specific times (described in the box below) to keep the sequence status continuously up to date, thus eliminating the need for the backup battery. As a result, there is no need for the user to replace any type of backup battery during the life of the camera, eliminating the worry of eventual vulnerability.
Note: -However, if the battery is removed for replacement during film rewinding or a long time exposure, there is possibility of camera mis-operation, and therefore a need for caution against this type of handling for those applications.
(c) Battery check Most electronic SLR camera has a battery check function for user to periodically check on the camera power status as once it is depleted, there is nothing you can do. Modern SLRs are generally very power thirst and it is a good practice to keep a spare for important assignment. The battery check function in the EOS-1N is a function which monitors the remaining capacity of the main power source. However, the popular symbol is not used in the EOS-1N, instead, a more delicate monitoring system is employed in the EOS-1N. Like the EOS-1, the battery check function is activated by pressing the battery check button inside the palm wing door. A resistor is used for the battery check function's current-drawing load, and the result of the check is displayed on the external LCD panel. The battery check display and the meaning of the indications are shown in Table below this page.
Canon Power Battery Pack BP-E1
Canon Power Booster Drive PDB-E1
Even if the battery check display indicates state "4" (see below), correctly exposed pictures will be taken as long as the shutter releases. However, before a power-consuming operation such as film loading, shutter release, film winding or rewinding, the camera automatically checks the battery level and prevents further operation if the battery is found to be exhausted. If this occurs, "bc" blinks in the LCD panel.
Battery Condition and Display Indications:-
Battery status LCD panel indication Meaning 1 + Battery is maintaining in an excellent condition state 2 + Battery is still usable, but have a new battery handy. 3 Battery will depleted soon 4 Battery is exhausted or installed battery is not workable. Replace with a new one.
Please take note that even if the battery indicator blinks or does not appear in the LCD panel during battery check, exposure will be correct as long as the shutter releases. When the battery power drops below a certain level, film advance and rewinding stop operating and “” blinks in the display. Film winding automatically resumes after a new battery is loaded. To resume rewinding, press the film rewind button ().
Note: -More information on how-to check and installed power cells and other related info is available at the Basic Info section. Relative: Various options on Power Sources for Canon EOS-1N
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Background and Various Issues | The Basic Features & various Setup
Manual & Auto Focusing | Metering Systems | Exposure Control | Viewfinder Optical
System Flash Photography (with Speedlite 540EZ extension & Selective info on Canon TTL Flash Models:-160E | 200E | 300EZ | 300TL | 420EZ | 430 EZ | 480EG | Macrolite | Other non-TTL Canon flash model
Reliability Issues:- Body Chassis | Shutter Unit | Electronic Circuitry | Film Transport & film handling Secondary Functions:- Custom Function Part One | Part Two | System Accessories:- Film Back Options - instruction for Command Back E1 | Macro/Close Up Part one | Part two and Part III Flash for Macro-Photography | Power Sources -BP-E1 | PDB-E1 | Focusing Screens | Remote Control with Wireless Remote Set LC-3 | System compatibility
Variants of Canon EOS-1N:- Canon EOS-1N RS | Canon/Kodak Digital DCS-1, 3 -5 & 520/560 Series | Full Technical Specification | Main Reference Map / Nomenclature | Resource Centre:- Comparative Charts between EOS-1 & EOS-1N / or with its active Competition(s) (Nikon); Quick Operational Reference Card (278k Gif File); Listings of 7-segment digital numbers/letters appeared on LCD display panel/viewfinders (HTML page); External Link:-Instruction Manual (3.3MB PDF file applicable for both Canon EOS-1N (RS). | Using EOS system for your photography | Bots & Nuts of EOS System - by Philip Chong |
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