The EF 50mm f/1.8 is an economy level lens (discontinued in 1990), which has been replaced by the EF 50mm f/1.8 II. The body is plastic but the lens mount is metal, and it features a distance window with infrared index. A 5 blade maximum aperture of f/1.8 gives this lens the ability to create depth of field effects.
The optical construction of this lens contains 6 lens elements, with no special elements. This lens uses a front extension focusing system, powered by an AFD motor. The front of the lens does not rotate when focusing, making it compatible with circular polarisers.
Auto-focus speed, despite the AFD motor, is moderately fast but audible.
Read more about this topic: Canon EF 50mm Lens