The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 18-55mm F3.5-5.6 SAM and the Sigma 17-70mm F2.8-4 DC OS HSM C 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 17-70mm F2.8-4 DC OS HSM C is the longer of the two lenses at 82mm. The Sony DT 18-55mm F3.5-5.6 SAM with a length of 69mm, is 13mm shorter. Besides being longer, the Sigma 17-70mm F2.8-4 DC OS HSM C also has a larger diameter of 79mm compared to the Sony DT 18-55mm F3.5-5.6 SAM's 70mm 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 18-55mm F3.5-5.6 SAM weighs 210g, which means it is 255g (54%) 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 Sony Alpha Mount for size comparison purposes.
Standard Lenses in Sony Alpha Mount for Size Comparison
Filter Threads
The Sony DT 18-55mm F3.5-5.6 SAM has a filter size of 55mm 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 55mm filters that we recommend you to consider for the Sony DT 18-55mm F3.5-5.6 SAM:
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 Sony DT 18-55mm F3.5-5.6 SAM and the Sigma 17-70mm F2.8-4 DC OS HSM C has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Sigma 17-70mm F2.8-4 DC OS HSM C is also available in Canon EF , Pentax KAF3, Sigma SA and Nikon F (DX) mounts.
Focal Range
Sony DT 18-55mm F3.5-5.6 SAM has a focal range of 18-55mm and
3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-82.5mm 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.
