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 and the Sigma 24-70mm F2.8 EX DG 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 28-75mm F2.8 Di III is the longer of the two lenses at 117mm. The Sigma 24-70mm F2.8 EX DG with a length of 116mm, is 1mm shorter. On the other hand, the Sigma 24-70mm F2.8 EX DG has a larger diameter of 89mm compared to the Tamron 28-75mm F2.8 Di III'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 28-75mm F2.8 Di III weighs 550g, which means it is 165g (23%) lighter than the Sigma 24-70mm F2.8 EX DG which has a weight of 715g.
Filter Threads
The Tamron 28-75mm F2.8 Di III has a filter size of 67mm whereas the Sigma 24-70mm F2.8 EX DG has a 82mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Tamron 28-75mm F2.8 Di III:
And these are the 82mm filters that we recommend for the Sigma 24-70mm F2.8 EX DG:
Lens Mounts
The Tamron 28-75mm F2.8 Di III has the Sony E lens mount whereas the Sigma 24-70mm F2.8 EX DG has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A9 III, Sony A7C Mark II and Sony A7CR for the Sony E Mount and Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount.
Sigma 24-70mm F2.8 EX DG is also available in Canon EF , Pentax KAF, Sigma SA and Nikon F (FX) mounts.
Focal Range
Tamron 28-75mm F2.8 Di III 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 Sigma 24-70mm F2.8 EX DG has a focal range of 24-70mm 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 36 - 105mm.