The type of photography that you are planning to use is an important decision factor. Here we have evaluated the PENTAX28-105mm F3.5-5.6 WR and the Sigma 24-105mm F4 DG 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 24-105mm F4 DG OS HSM is the longer of the two lenses at 109mm. The PENTAX28-105mm F3.5-5.6 WR with a length of 87mm, is 22mm shorter. Besides being longer, the Sigma 24-105mm F4 DG OS HSM also has a larger diameter of 89mm compared to the PENTAX28-105mm F3.5-5.6 WR's 73mm 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. PENTAX28-105mm F3.5-5.6 WR weighs 440g, which means it is 445g (50%) lighter than the Sigma 24-105mm F4 DG OS HSM which has a weight of 885g.
Filter Threads
The PENTAX28-105mm F3.5-5.6 WR has a filter size of 62mm whereas the Sigma 24-105mm F4 DG OS HSM has a 82mm 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 PENTAX28-105mm F3.5-5.6 WR:
And these are the 82mm filters that we recommend for the Sigma 24-105mm F4 DG OS HSM:
Lens Mounts
The PENTAX28-105mm F3.5-5.6 WR has the Pentax KAF3 lens mount whereas the Sigma 24-105mm F4 DG OS HSM has the Sony Alpha 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 KAF3 Mount and Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount.
Sigma 24-105mm F4 DG OS HSM is also available in Canon EF , Nikon F (FX) and Sigma SA mounts.
Focal Range
PENTAX28-105mm F3.5-5.6 WR has a focal range of 28-105mm and
3.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 157.5mm.
On the other hand, the Sigma 24-105mm F4 DG OS HSM has a focal range of 24-105mm and 4.4X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 36 - 157.5mm.
