The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 50mm f1.8 II and the Canon 50mm f1.4 USM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Canon 50mm f1.4 USM is the longer of the two lenses at 51mm. The Canon 50mm f1.8 II with a length of 41mm, is 10mm shorter. Besides being longer, the Canon 50mm f1.4 USM also has a larger diameter of 74mm compared to the Canon 50mm f1.8 II's 68mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Canon 50mm f1.8 II weighs 130g, which means it is 160g (55%) lighter than the Canon 50mm f1.4 USM which has a weight of 290g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Canon EF Mount for size comparison purposes.
Standard Prime Lenses in Canon EF Mount for Size Comparison
Both the Canon 50mm f1.8 II and the Canon 50mm f1.4 USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Both lenses have the same focal range of 50mm but while Canon 50mm f1.8 II has the fastest aperture of F1.8, the Canon 50mm f1.4 USM's widest aperture value is F1.4.