The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 17-40mm f1.8 and the Tamron 17-70 F2.8 Di III-A 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 17-70 F2.8 Di III-A VC is the longer of the two lenses at 119mm. The Sigma 17-40mm f1.8 with a length of 116mm, is 3mm shorter. Besides being longer, the Tamron 17-70 F2.8 Di III-A VC also has a larger diameter of 75mm compared to the Sigma 17-40mm f1.8's 73mm 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 17-70 F2.8 Di III-A VC weighs 525g, 1% (10g) lighter than the Sigma 17-40mm f1.8's weight of 535g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Fujifilm X Mount for size comparison purposes.
Standard Lenses in Fujifilm X Mount for Size Comparison
Filter Threads
Both the Sigma 17-40mm f1.8 and the Tamron 17-70 F2.8 Di III-A 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
Both the Sigma 17-40mm f1.8 and the Tamron 17-70 F2.8 Di III-A VC has the same Fujifilm X lens mount. Some of the latest released cameras that are compatible with the Fujifilm X lenses are Fujifilm X-T30 III, Fujifilm X-E5 and Fujifilm X-M5.
Sigma 17-40mm f1.8 is also available in the Sony E , Leica L and Canon RF mounts.
Tamron 17-70 F2.8 Di III-A VC is also available in Sony E mount.
Focal Range
Sigma 17-40mm f1.8 has a focal range of 17-40mm and
2.4X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
25.5-60mm when used on a APS-C / DX format camera.
On the other hand, the Tamron 17-70 F2.8 Di III-A VC has a focal range of 17-70mm and 4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-105mm when used on a APS-C / DX format camera.
