The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 85mm F1.4L IS USM and the Tamron 45mm F1.8 Di VC USD for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Canon EF 85mm F1.4L IS USM is the longer of the two lenses at 105mm. The Tamron 45mm F1.8 Di VC USD with a length of 92mm, is 13mm shorter. Besides being longer, the Canon EF 85mm F1.4L IS USM also has a larger diameter of 87mm compared to the Tamron 45mm F1.8 Di VC USD's 80mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Tamron 45mm F1.8 Di VC USD weighs 520g, 45% (430g) lighter than the Canon EF 85mm F1.4L IS USM's weight of 950g.
Filter Threads
The Canon EF 85mm F1.4L IS USM has a filter size of 77mm whereas the Tamron 45mm F1.8 Di VC USD has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Canon EF 85mm F1.4L IS USM:
And these are the 67mm filters that we recommend for the Tamron 45mm F1.8 Di VC USD:
Lens Mounts
The Canon EF 85mm F1.4L IS USM has the Canon EF lens mount whereas the Tamron 45mm F1.8 Di VC USD has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount and Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount.
Tamron 45mm F1.8 Di VC USD is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Canon EF 85mm F1.4L IS USM is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
136mm.
On the other hand, the 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 1.5x crop, it provides a 35mm (FF) equivalent of 67.5mm.