The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 28-75mm F2.8 Di III VXD G2 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 Tamron 28-75mm F2.8 Di III VXD G2 with a length of 118mm, is 1mm shorter. On the other hand, the Tamron 28-75mm F2.8 Di III VXD G2 has a larger diameter of 76mm compared to the Tamron 17-70 F2.8 Di III-A VC's 75mm diameter.
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Below you can find a scaled side-by-side image of Tamron 28-75mm F2.8 Di III VXD G2 and Tamron 17-70 F2.8 Di III-A VC to get a better idea of how their sizes compare in real life.
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, 2% (15g) lighter than the Tamron 28-75mm F2.8 Di III VXD G2's weight of 540g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Sony E Mount for size comparison purposes.
Standard Lenses in Sony E Mount for Size Comparison
Filter Threads
Both the Tamron 28-75mm F2.8 Di III VXD G2 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 Tamron 28-75mm F2.8 Di III VXD G2 and the Tamron 17-70 F2.8 Di III-A VC has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Tamron 28-75mm F2.8 Di III VXD G2 is also available in Nikon Z mount.
Tamron 17-70 F2.8 Di III-A VC is also available in Fujifilm X mount.
Focal Range
Tamron 28-75mm F2.8 Di III VXD G2 has a focal range of 28-75mm and
2.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 112.5mm.
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.