Canon's 1989 50mm f1.0 lens was only ever produced in small numbers, and at f/1.0 was the fastest Canon lens in production. The optical construction of this lens contains 11 lens elements in 9 groups, including two ground and polished aspherical lens elements. It has a floating front extension focusing system, using a ring-type USM motor.
Not at all easy to find - expect to pay a lot of money for a used example.
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