The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-50mm f2.8 XR II LD and the Sigma 17-70mm F2.8-4 DC OS HSM C for their suitability to various photography scenarios:
Size and Weight Comparison
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 17-50mm f2.8 XR II LD weighs 430g, which means it is 35g (7%) 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 Nikon F (DX) Mount for size comparison purposes.
Standard Lenses in Nikon F (DX) Mount for Size Comparison
Filter Threads
The Tamron 17-50mm f2.8 XR II LD has a filter size of 67mm 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 67mm filters that we recommend you to consider for the Tamron 17-50mm f2.8 XR II LD:
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 17-50mm f2.8 XR II LD and the Sigma 17-70mm F2.8-4 DC OS HSM C has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D3500, Nikon D7500 and Nikon D5600.
Tamron 17-50mm f2.8 XR II LD is also available in the Canon EF , Sony Alpha and Pentax KAF mounts.
Sigma 17-70mm F2.8-4 DC OS HSM C is also available in Canon EF , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Tamron 17-50mm f2.8 XR II LD has a focal range of 17-50mm and
2.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
25.5-75mm when used on a APS-C / DX format camera.
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.
