Modern Classic SLRs Series :
Canon F1 - Servo EE Finder (Index)


Servo EE Finder on F-1.image (17k Jpeg)

just Download an
Instruction Manual
for EE Servo Finder Unit- courtesy of Mr. Christian Rollinger

Full Aperture Metering EE Servo EE Finder * Other interchangeable Finder/Prisms like Waist Level Finder, and the innovative Speed Finder, and some Viewing accessories, Click here. Another interesting dedicated Prism designed for the Canon F-1 is the Booster T Finder and a Electronic finder... wow!

Technical Descriptions | How to use (Basic & Detailed) the Servo EE Finder

* These finders of yesteryear could be quite tricky to use, if you have bought one from the used market, better check on these pages for reference. The Servo EE Finder is a viewfinder provided with an automatic exposure control which works by means of an electronic circuit powering a servo motor. One of the features of the F-1 system is the practical application of available electronic technology on its F-1 as accessories. By the way, it can be said that the Servo EE Finder is an improvement of the full aperture metering mechanism of the Canon F-1 to be able to decide exposure with EE at full aperture. Though Canon claimed this product is Canon's exclusive but Nikon does has few similar options as a added on device for its F2 during the seventies, like the EE Aperture Control Unit for comparable automation (Like the Canon F-1, although the F2 did not have AE capability built into the body, Shutter Priority Exposure was possible with the DP2, DP3, and DP3 finders when used in conjunction with EE Attachment DS-1, DS-2, and DS-12, respectively. The motor attachments (Battery operated as well) to the finders works like shutter priority automation by physically turning the aperture ring to the desired f number on the lens). For a view of how the Nikon EE Attachment looks like, click here for a view on a Nikon F2S or * here for Nikon F2AS for cross reference.

I think in certain area, we need the F2 to compare as where the Canon F-1 direct competition was primarily aimimg at. The F-1 system includes a Motor Drive Unit for power-driven photography, and the Film Chamber 250 for extending the capabilities of the Motor Drive Unit. Together with the timer, this system relies completely on electric control, as do the various other accessories for remote control. Fully automatic photography is possible through the combination of these accessories.

Aperture Control The EE coupler controls the preset aperture positions of the FD lens from the body of the F-1 because the mechanism of the diaphragm of the FD lens is completely cut off from the preset aperture ring on the outside of the camera. When the ring is set at the green (EE) mark. The servo motor drives the aperture signal lever to preset correct exposure while the diaphragm remains fully open. Since the servo motor can yield quite a strong drive, a very smooth operation can be achieved. The Servo EE has a center weighted averaging meter since such metering pattern is preferred to automatic aperture control during that period, as one noticed - all the engingeers from respective manufacturers were cracking their head to design devices to hooked on the finder to perform "capabilities" - creativeness and imagination was extended to its fullest becoz' Canon F-1, Pentax MX, Nikon's F2 (Minolta XK if one still can recalled) are basically a mechanical camera. Thus, to those who appreciates all mechanically-function-cameras - always thought the '70 was the prime era for mechanical cameras.

The CdS photocells are located on both sides of the eyepiece. The fairly sensitive photocells are independent from the built-in exposure meter of the F-1 body, and are connected directly to the servo circuit. This viewfinder has its own shutter speed dial coupled to the F-1 body. It employs the shutter priority method to set correct exposures automatically according to shutter speed and ASA film speed. This viewfinder's metering range is the same as the camera's from EV 2.5 to EV 18, with the ASA set at 100. Every shutter speed except "B" is possible. Since one of the characteristics of the EE automatic system is that exposure settings are automatically decided to meet the light intensity of the subject, this viewfinder ensures absolute efficiency for continuous photography of subjects whose light intensity is particularly unstable and for unmanned photography with remote control. Furthermore, since metering control can be adjusted by means of a switch for continuous shots, single shot, locking and manual setting, this serves to make the most effective use of the EE. In single shot metering, for instance, if the switch is turned off by keeping a finger off after metering, the automatic exposure mechanism is locked. This is ideal for close-up readings against the light when full automation would give incorrect exposure. Exposure can also be decided by manual aperture control as well..

Viewfinder Information As the pentaprism is identical to the eye-level viewfinder, its field of view and magnification ratios are the same as those of the eye-level viewfinder. However, since the metering information differs from that of the matching needle system, a special information window is incorporated in order to see the f/stop, meter need le, and the exposure warning mark. By setting the maximum aperture index, the f/stop value and the warning mark in the information window move up and down to indicate the proper exposure range. This viewfinder's needle is not an ordinary one, but serves as an indicator coupled with the motordriven mechanism so that you can read the f/stop value with a glance at the information window.

The Circuit This structure consists of the bridge circuit which has a CdS photocell and the servo circuit. The constants, film speed and shutter speed are set in the bridge circuit. When the amount of light changes and the balance of the bridge circuit is broken, a voltage signal is added to the electronic circuit to drive the servo motor. This moves the EE signal plate up and down by means of the gear train. It also moves the aperture lever of the lens through the EE coupling arm. When the bridge is balanced again, all operations stop and the lens is set to the correct aperture. The operation is switched off when beyond the metering range to avoid unnecessary power consumption. A constant-voltage circuit is used to increase stability with a constant supply of 9V, although the operation can be faithfully performed even when the voltage is changed. Thus, this circuit features a long time operation that is not affected by the voltage fluctuations.

Power Source When using the Servo EE Finder alone, load the Magazine 12V with 8 penlight batteries. When it is used together with a Motor Drive Unit, the Magazine 15V with 10 penlight batteries should be used instead of the Magazine 1 2V. When the Motor Drive MF is used, the Finder shares the power source in the MF's grip. In each case a voltage of 9V is supplied by means of the constant-voltage circuit for stable operation.

Contact Point of the Servo EE Control The contact point is visible in the center when the bottom cover of the camera is removed. It serves as the terminal to supply the power source when the Finder is used together with the Motor Drive Unit, and is connected to the Servo EE circuit switch in the F-1 body. This switch interrupts the power to the Servo EE during exposure. If the power were not turned off, the servo motor would change the aperture during long exposures because the light cannot reach the CdS when the mirror is up. The power is interrupted when the diaphragm is stopped down, so the Servo EE will not function if the stopped-down lever is pushed. This circuit only functions when the Motor Drive Unit and Battery Connector MD are used, so if the Servo EE Finder is used alone, it must be connected directly to the battery case. If the Battery Connector MD is used, the Motor Drive Unit must be connected or the Servo EE Finder will not function.

Apart from the few prisms mentioned at the top of the page, another interesting dedicated Prism/Finder designed for Canon F-1 is the Booster T Finder

Also check: Booster for Canon Pellix and FTQL

Concept | Reliability Issue | Motor Drive Units | Macro | EE Servo / Booster Finder | Bulk Film Back | CAT (Flash System | F1 High Speed | ODF-1 | Placid | Assembling Diaphragm | Canon FD & FDn lenses

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