The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 20mm f2.8 USM and the Tamron 16-300mm f3.5-6.3 II VC PZD 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 16-300mm f3.5-6.3 II VC PZD is the longer of the two lenses at 100mm. The Canon 20mm f2.8 USM with a length of 71mm, is 29mm shorter. On the other hand, the Canon 20mm f2.8 USM has a larger diameter of 78mm compared to the Tamron 16-300mm f3.5-6.3 II VC PZD's 75mm 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. Canon 20mm f2.8 USM weighs 405g, which means it is 135g (25%) lighter than the Tamron 16-300mm f3.5-6.3 II VC PZD which has a weight of 540g.
Filter Threads
The Canon 20mm f2.8 USM has a filter size of 72mm whereas the Tamron 16-300mm f3.5-6.3 II VC PZD 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 72mm filters that we recommend you to consider for the Canon 20mm f2.8 USM:
And these are the 67mm filters that we recommend for the Tamron 16-300mm f3.5-6.3 II VC PZD:
Lens Mounts
Both the Canon 20mm f2.8 USM and the Tamron 16-300mm f3.5-6.3 II VC PZD 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 16-300mm f3.5-6.3 II VC PZD is also available in Nikon F (DX) and Sony Alpha mounts.
Focal Range
Canon 20mm f2.8 USM is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
On the other hand, the Tamron 16-300mm f3.5-6.3 II VC PZD has a focal range of 16-300mm and 18.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.6-480mm when used on a APS-C / DX format camera.