The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic S 20-60mm F3.5-5.6 and the Sigma 17-70mm F2.8-4 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 17-70mm F2.8-4 DC OS HSM is the longer of the two lenses at 89mm. The Panasonic S 20-60mm F3.5-5.6 with a length of 87mm, is 2mm shorter. Besides being longer, the Sigma 17-70mm F2.8-4 DC OS HSM also has a larger diameter of 79mm compared to the Panasonic S 20-60mm F3.5-5.6's 77mm 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. Panasonic S 20-60mm F3.5-5.6 weighs 350g, which means it is 170g (32%) lighter than the Sigma 17-70mm F2.8-4 DC OS HSM which has a weight of 520g.
Filter Threads
The Panasonic S 20-60mm F3.5-5.6 has a filter size of 67mm whereas the Sigma 17-70mm F2.8-4 DC OS HSM 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 Panasonic S 20-60mm F3.5-5.6:
And these are the 72mm filters that we recommend for the Sigma 17-70mm F2.8-4 DC OS HSM:
Lens Mounts
The Panasonic S 20-60mm F3.5-5.6 has the Leica L lens mount whereas the Sigma 17-70mm F2.8-4 DC OS HSM has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Leica SL3, Panasonic S5 II and Panasonic S5 II X for the Leica L Mount and Sony A68, Sony A77 II and Sony A58 for the Sony Alpha Mount.
Sigma 17-70mm F2.8-4 DC OS HSM is also available in Canon EF , Pentax KAF3, Sigma SA and Nikon F (DX) mounts.
Focal Range
Panasonic S 20-60mm F3.5-5.6 has a focal range of 20-60mm and
3.0X zoom ratio .
On the other hand, the Sigma 17-70mm F2.8-4 DC OS HSM 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.