The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 28-70mm F2.8 DG DN C and the Tamron AF 28-75mm f2.8 XR LD 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 28-70mm F2.8 DG DN C is the longer of the two lenses at 102mm. The Tamron AF 28-75mm f2.8 XR LD with a length of 92mm, is 10mm shorter. On the other hand, the Tamron AF 28-75mm f2.8 XR LD has a larger diameter of 73mm compared to the Sigma 28-70mm F2.8 DG DN C'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. Sigma 28-70mm F2.8 DG DN C weighs 470g, which means it is 40g (7%) lighter than the Tamron AF 28-75mm f2.8 XR LD which has a weight of 510g.
Filter Threads
Both the Sigma 28-70mm F2.8 DG DN C and the Tamron AF 28-75mm f2.8 XR LD 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
The Sigma 28-70mm F2.8 DG DN C has the Sony E lens mount whereas the Tamron AF 28-75mm f2.8 XR LD 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 28-70mm F2.8 DG DN C is also available in Leica L mount.
Tamron AF 28-75mm f2.8 XR LD is also available in Canon EF , Nikon F (FX) and Pentax KAF mounts.
Focal Range
Sigma 28-70mm F2.8 DG DN C has a focal range of 28-70mm and
2.5X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 105mm.
On the other hand, the Tamron AF 28-75mm f2.8 XR LD 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.