which could read as low as EV −3.5. Just like the metering range was shifted towards the dark side, this finder also shift the shutter speeds the camera provided towards the long end. Instead of the normal range (1 s – 1/2000 s), the Booster T Finder gave 60 s – 1/60 s. The shutter speed dial on the finder locked on to the camera's normal shutter dial and drove it through a coupling pin for the standard range of 1 s – 1/60 s. The finder also had a trigger button, which went through the finder down to the normal trigger button. When the Booster's shutter speed dial was turned further, towards longer times, the camera's dial stopped at the B(ulb) setting, and the finder kept the trigger button pressed for the duration of the exposure. The mechanics of this connection also resulted in the oddity that there was no 2 s setting, but 4, 3 and 1 seconds. The Servo EE Finder added shutter priority automatic exposure to the F-1. A servo mechanism in the finder drove the aperture lever on the lens, stopping it down to the correct value. This finder used the same coupling pin on the shutter speed dial as the Booster T Finder did, to sync the finder's shutter speed setting with the camera. It required a cord connected battery magazine (8AAs) or the Motor Drive MF and a special power cord. Motor drives The originally available Motor Drive was named the "Motor Drive Unit". It was commonly referred to as the Motor Drive MD – because all of the accessories had MD in their suffix, but that was not the official designation. The Motor Drive Unit originally required a corded battery pack (10 AAs) making it unwieldy for field or sports action use. A later battery pack that direct connected to the unit became available. The unit also contained a built intervalometer for delays up to 1 frame per minute. The maximum speed was 3 frames per second. In 1972 Canon made a special Modification of the F-1 called the "High Speed Motor Drive Camera". It had a fixed pellicle (semi transparent) mirror, the motor drive motors were a permanent attachment (the camera's wind lever was removed – making it impossible to use without the motor drive). Maximum speed was 9 frame/sec – the fastest available at the time. Its use at the