Modern Classic SLRs Series :
Canon F1 - Booster T Finder (Operation)


This section covers: Metering with Booster; Metering with Camera
Metering With High Film Speed;Using External Power Source; Attaching the; Magnifier R

Earlier section covers: Loading the Battery; Checking the Battery; Attachment *

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Credit: Tony Kano (Ex-Regional Head (Asia), Richard Yeow (Division Head-Malaysia) of Canon Marketing who share the same enthuasism for making this site possible for all Canon Fans.

We strongly suggest to use a detailed illustration of various dials and control buttons on the Booster T Finder & Canon F-1 Body for cross reference.


Metering with the Booster

Metering with the Booster is used when long-time exposures of 3 seconds or longer are required for dimly lit subjects, or when the aperture is opened and the shutter speed is increased in order to shoot a subject without sufficient light.

The orange-color scale on the shutter speed dials used for long-time exposures from 3 to 60 seconds set by the timer. Switching is performed at the position of 3 seconds by pulling the switch knob. At this time, the shutter speed dial on the camera is set at "B". The timer starts working when the shutter release button is depressed, and exposure is decided automatically even after withdrawing the finger from the button. The white-coloured scale is set to match the scale on the camera side.


Operation for Metering:

Set the meter switch at "ON".

Turn the shutter speed dial to the orange colored side so that it stops at the position of 3 seconds.

When it is turned beyond that while pulling the timer switch knob, it may be set at the extended time scale.

Adjust focusing through the viewfinder with aperture fully opened to decide the composition.

5. Start metering by turning the knob of the eyepiece shutter to the "C" side. Then the eyepiece shutter will close and the switch will be set at the side of the Booster. Do not forget to turn the knob or it will not be possible to perform metering because the switch serves also to prevent errors caused by the backflow of light from the finder.

At the same time, the lamp on the-meter window lights up to indicate that metering is performed by the Booster.

7. Push the metering lever of the camera down to lock it at stopped down metering.

Turn the shutter dial on the aperture ring and regulate the meter needle to set it at the black index. The (3side indicates over exposure and (3 side indicates under exposure.

When metering with the Booster, the speed of response is slightly slower than ordinary metering due to the low volume of light. Therefore, it is necessary to wait until the needle has stopped moving. Under extremely dim light conditions of under EV 0, it takes two or three minutes, and with sufficient light it takes from 10 to 30 seconds.

Depress the shutter release button after exposure is decided. Then the button is locked and the timer works according to the shutter speed. Exposure is automatically set after removing the finger from the button.

The meter lamp blinks at intervals of about one second to indicate exposure is in process.

When exposure ends, the shutter release button returns to its former position.

Metering with the Camera

Metering with the camera is performed when the subject is brighter than the Booster's metering range.



1. Turn the shutter speed dial to the whitecolored scale of the high speed side. When it goes over 3, the dials on the Booster and the camera automatically lock together.

When the metering range comes within that of the camera, the lamp of the meter window goes out and the finder lamp on the Booster T Finder lights up to indicate that the camera is doing the metering.

This lamp is placed to illuminate the meter window on the right-hand side in the field of view of the finder to be able to see the information.

Turn the knob of the eyepiece shutter, and return the metering lever for full aperture metering.

Proper exposure can be obtained with ordinary full aperture metering by matching the aperture needle and the meter needle in the field of view of the viewfinder.

Metering with High Film Speed

Film speeds up to ASA 2000 can be used with the camera, but with the Booster up to 12800 are possible. When film speed is slower than ASA 2000 and both the camera and the Booster are set at the same speed, metering can be performed by either side. When the ASA is over 2000 and can only be set at the Booster side, metering must be performed by the Booster only.


1.When the shutter release button is depressed at the timer scale position before winding, the button locks and the count starts. Do not mistake this for an exposure.
2. If the shutter release button is depressed when the main switch is at "OFFi', the button locks. However, it will be released by turning the dial to the high speed side.
3. Since the silver battery is consumed rather fast, cut the switch off every time the operation ends.

Using the External Power Source


At low temperatures of 0°C or below, the quality of the battery's performance decreases and its consumption becomes excessive. Therefore, it is recommended to use the battery case as an external power source for more efficiency. Load the Battery Magazine 12V (with 8 penlight batteries) on the battery case. Use the Canon Cord 6V 2B for connecting the battery case to the Booster T Finder.

Attaching the Cord

1. Take the silver battery out of the Booster T Finder, and screw the cord's terminal in its stead.

2. Plug the 6V2B Cord in the battery case and screw it tight with the ring.

Magnifier R

The Canon Magnifier can be attached to the eyepiece. It magnifies the rangefinder section for accurate focusing. Because it can be swung up and clamped, the entire field of view can be viewed after focusing.

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