The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 28-80mm f3.5-5.6 and the Sigma 17-70mm F2.8-4 DC OS HSM C 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. Sigma 17-70mm F2.8-4 DC OS HSM C is the longer of the two lenses at 82mm. The Tamron AF 28-80mm f3.5-5.6 with a length of 70mm, is 12mm shorter. Besides being longer, the Sigma 17-70mm F2.8-4 DC OS HSM C also has a larger diameter of 79mm compared to the Tamron AF 28-80mm f3.5-5.6's 72mm 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 AF 28-80mm f3.5-5.6 weighs 237g, which means it is 228g (49%) lighter than the Sigma 17-70mm F2.8-4 DC OS HSM C which has a weight of 465g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Sony Alpha Mount for size comparison purposes.
Standard Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
The Tamron AF 28-80mm f3.5-5.6 has a filter size of 58mm whereas the Sigma 17-70mm F2.8-4 DC OS HSM C has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Tamron AF 28-80mm f3.5-5.6:
And these are the 72mm filters that we recommend for the Sigma 17-70mm F2.8-4 DC OS HSM C:
Lens Mounts
Both the Tamron AF 28-80mm f3.5-5.6 and the Sigma 17-70mm F2.8-4 DC OS HSM C has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Tamron AF 28-80mm f3.5-5.6 is also available in the Canon EF , Nikon F (FX) and Pentax KAF mounts.
Sigma 17-70mm F2.8-4 DC OS HSM C is also available in Canon EF , Pentax KAF3, Sigma SA and Nikon F (DX) mounts.
Focal Range
Tamron AF 28-80mm f3.5-5.6 has a focal range of 28-80mm and
2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 120mm.
On the other hand, the Sigma 17-70mm F2.8-4 DC OS HSM C 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.
