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 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 17-40mm f1.8 is the longer of the two lenses at 116mm. The Tamron AF 28-75mm f2.8 XR LD with a length of 92mm, is 24mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 73mm.
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 28-75mm f2.8 XR LD weighs 510g, 4% (25g) lighter than the Sigma 17-40mm f1.8's weight of 535g.
Filter Threads
Both the Sigma 17-40mm f1.8 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 17-40mm f1.8 has the Sony E lens mount whereas the Tamron AF 28-75mm f2.8 XR LD has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Sony ZV-E10 II, Sony A6700 and Sony FX30 for the Sony E Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Sigma 17-40mm f1.8 is also available in the Leica L , Fujifilm X and Canon RF mounts.
Tamron AF 28-75mm f2.8 XR LD is also available in Nikon F (FX) , Sony Alpha and Pentax KAF mounts.
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 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 1.6x crop, it provides a 35mm (FF) equivalent of 44.8 - 120mm.
