The EF 50mm lenses are a group of normal prime lenses made by Canon that share the same focal length.
These lenses have an EF type mount, that fits the Canon EOS line of cameras.
When used on a digital EOS body with a field of view compensation factor of 1.6x, such as the Canon EOS 400D, it provides a narrower field of view, equivalent to an 80mm lens mounted on a 35mm frame body. With a 1.3x body such as the Canon EOS-1D Mark III, it provides a less narrow field of view, equivalent to an 65mm lens mounted on a 35mm frame body.
Six EF 50mm lenses have been developed and sold. Two are L series lenses and three have Ultrasonic motors.
Since the f/1.2L, f/1.4 and f/1.8 lenses can provide very similar wide-aperture shots but have very different price tags, they have naturally been the subject of many in depth comparisons. I took all these shots in a Botanic garden.