The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 45mm F1.8 Di VC USD and the Canon 50mm f1.2L 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. Tamron 45mm F1.8 Di VC USD is the longer of the two lenses at 92mm. The Canon 50mm f1.2L USM with a length of 66mm, is 26mm shorter. On the other hand, the Canon 50mm f1.2L USM has a larger diameter of 86mm compared to the Tamron 45mm F1.8 Di VC USD's 80mm 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. Tamron 45mm F1.8 Di VC USD weighs 540g, which means it is 40g (6%) lighter than the Canon 50mm f1.2L USM which has a weight of 580g.
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
Lens Mounts
Both the Tamron 45mm F1.8 Di VC USD and the Canon 50mm f1.2L 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.
Tamron 45mm F1.8 Di VC USD is also available in Nikon F (FX) and Sony Alpha mounts.
Focal Range
Tamron 45mm F1.8 Di VC USD is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 72mm.
Canon 50mm f1.2L USM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 80mm.