The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 20-40mm F2.8 VXD and the Tamron 85mm F1.8 VC 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. Tamron 85mm F1.8 VC is the longer of the two lenses at 91mm. The Tamron 20-40mm F2.8 VXD with a length of 86mm, is 5mm shorter. Besides being longer, the Tamron 85mm F1.8 VC also has a larger diameter of 85mm compared to the Tamron 20-40mm F2.8 VXD's 74mm 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 20-40mm F2.8 VXD weighs 365g, which means it is 335g (47%) lighter than the Tamron 85mm F1.8 VC which has a weight of 700g.
Filter Threads
Both the Tamron 20-40mm F2.8 VXD and the Tamron 85mm F1.8 VC have the same Filter thread size of 67mm.
Below are links to the 67mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Tamron 20-40mm F2.8 VXD has the Sony E lens mount whereas the Tamron 85mm F1.8 VC has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount.
Tamron 85mm F1.8 VC is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Tamron 20-40mm F2.8 VXD has a focal range of 20-40mm and
2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
30 - 60mm.
On the other hand, the Tamron 85mm F1.8 VC is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 127.5mm.
