The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 17-50mm F2.8 EX DC OS HSM and the Pentax smc 16-50mm F2.8 ED 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 smc 16-50mm F2.8 ED is the longer of the two lenses at 99mm. The Sigma 17-50mm F2.8 EX DC OS HSM with a length of 92mm, is 7mm 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.
Filter Threads
Both the Sigma 17-50mm F2.8 EX DC OS HSM and the Pentax smc 16-50mm F2.8 ED 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 Sigma 17-50mm F2.8 EX DC OS HSM has the Pentax KAF3 lens mount whereas the Pentax smc 16-50mm F2.8 ED has the Pentax KAF2 lens mount. Some of the latest released cameras that are compatible with these mounts are , and for the Pentax KAF3 Mount and , and for the Pentax KAF2 Mount.
Sigma 17-50mm F2.8 EX DC OS HSM is also available in the Canon EF , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
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.
On the other hand, the Pentax smc 16-50mm F2.8 ED 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.
