The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 18-270mm f3.5-6.3 II VC PZD and the Nikon 20mm f2.8D 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 18-270mm f3.5-6.3 II VC PZD is the longer of the two lenses at 88mm. The Nikon 20mm f2.8D with a length of 43mm, is 45mm shorter. Besides being longer, the Tamron 18-270mm f3.5-6.3 II VC PZD also has a larger diameter of 74mm compared to the Nikon 20mm f2.8D's 69mm 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. Nikon 20mm f2.8D weighs 270g, 40% (180g) lighter than the Tamron 18-270mm f3.5-6.3 II VC PZD's weight of 450g.
Filter Threads
Both the Tamron 18-270mm f3.5-6.3 II VC PZD and the Nikon 20mm f2.8D have the same Filter thread size of 62mm.
Below are links to the 62mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Tamron 18-270mm f3.5-6.3 II VC PZD has the Nikon F (DX) lens mount whereas the Nikon 20mm f2.8D has the Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount and Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount.
Tamron 18-270mm f3.5-6.3 II VC PZD is also available in Canon EF mount.
Focal Range
Tamron 18-270mm f3.5-6.3 II VC PZD has a focal range of 18-270mm and
15.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-405mm when used on a APS-C / DX format camera.
On the other hand, the Nikon 20mm f2.8D is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 30mm.