The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 16-105mm F3.5-5.6 and the Sigma 18-125mm F3.8-5.6 DC OS HSM 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 18-125mm F3.8-5.6 DC OS HSM is the longer of the two lenses at 89mm. The Sony DT 16-105mm F3.5-5.6 with a length of 83mm, is 6mm shorter. Besides being longer, the Sigma 18-125mm F3.8-5.6 DC OS HSM also has a larger diameter of 74mm compared to the Sony DT 16-105mm 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. Sony DT 16-105mm F3.5-5.6 weighs 470g, which means it is 20g (4%) lighter than the Sigma 18-125mm F3.8-5.6 DC OS HSM which has a weight of 490g.
Filter Threads
The Sony DT 16-105mm F3.5-5.6 has a filter size of 62mm whereas the Sigma 18-125mm F3.8-5.6 DC OS HSM has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 62mm filters that we recommend you to consider for the Sony DT 16-105mm F3.5-5.6:
And these are the 67mm filters that we recommend for the Sigma 18-125mm F3.8-5.6 DC OS HSM:
Lens Mounts
The Sony DT 16-105mm F3.5-5.6 has the Sony Alpha lens mount whereas the Sigma 18-125mm F3.8-5.6 DC OS HSM has the Sigma SA lens mount. Some of the latest released cameras that are compatible with these mounts are Sony A68, Sony A77 II and Sony A58 for the Sony Alpha Mount and Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 18-125mm F3.8-5.6 DC OS HSM is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Sony DT 16-105mm F3.5-5.6 has a focal range of 16-105mm and
6.6X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
24-157.5mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-125mm F3.8-5.6 DC OS HSM has a focal range of 18-125mm and 6.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-187.5mm when used on a APS-C / DX format camera.