The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 20mm F2.8 Di III OSD M1:2 and the Tamron 17-28mm F2.8 Di III 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 17-28mm F2.8 Di III is the longer of the two lenses at 99mm. The Tamron 20mm F2.8 Di III OSD M1:2 with a length of 64mm, is 35mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 73mm.
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 20mm F2.8 Di III OSD M1:2 weighs 220g, which means it is 200g (47%) lighter than the Tamron 17-28mm F2.8 Di III which has a weight of 420g.
Filter Threads
Both the Tamron 20mm F2.8 Di III OSD M1:2 and the Tamron 17-28mm F2.8 Di III 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
Both the Tamron 20mm F2.8 Di III OSD M1:2 and the Tamron 17-28mm F2.8 Di III has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony FX5, Sony A7R VI and Sony A7 V.
Focal Range
Tamron 20mm F2.8 Di III OSD M1:2 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.
On the other hand, the Tamron 17-28mm F2.8 Di III has a focal range of 17-28mm and 1.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 25.5 - 42mm.
