The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 16-50mm F2.8 ED PLM AW and the Sigma 17-50mm F2.8 EX 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. Pentax 16-50mm F2.8 ED PLM AW is the longer of the two lenses at 117mm. The Sigma 17-50mm F2.8 EX DC OS HSM with a length of 92mm, is 25mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 84mm.
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. Sigma 17-50mm F2.8 EX DC OS HSM weighs 565g, 20% (147g) lighter than the Pentax 16-50mm F2.8 ED PLM AW's weight of 712g.
Filter Threads
Both the Pentax 16-50mm F2.8 ED PLM AW and the Sigma 17-50mm F2.8 EX DC OS HSM have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Pentax 16-50mm F2.8 ED PLM AW has the Pentax KAF4 lens mount whereas the Sigma 17-50mm F2.8 EX DC OS HSM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF4 Mount and , and for the Pentax KAF3 Mount.
Sigma 17-50mm F2.8 EX DC OS HSM is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Pentax 16-50mm F2.8 ED PLM AW has a focal range of 16-50mm and
3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
24-75mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 17-50mm F2.8 EX DC OS HSM 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.
