The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-200mm f3.5-6.3 II DC OS HSM and the Sigma 18-125mm F3.8-5.6 DC 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 18-125mm F3.8-5.6 DC HSM is the longer of the two lenses at 89mm. The Sigma 18-200mm f3.5-6.3 II DC OS HSM with a length of 88mm, is 1mm shorter. On the other hand, the Sigma 18-200mm f3.5-6.3 II DC OS HSM has a larger diameter of 75mm compared to the Sigma 18-125mm F3.8-5.6 DC HSM's 74mm 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.
Filter Threads
Both the Sigma 18-200mm f3.5-6.3 II DC OS HSM and the Sigma 18-125mm F3.8-5.6 DC HSM have the same Filter thread size of 62mm.
Below are links to the 62mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Sigma 18-200mm f3.5-6.3 II DC OS HSM has the Sigma SA lens mount whereas the Sigma 18-125mm F3.8-5.6 DC HSM has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount and , and for the Pentax KAF3 Mount.
Sigma 18-200mm f3.5-6.3 II DC OS HSM is also available in the Canon EF and Nikon F (DX) mounts.
Sigma 18-125mm F3.8-5.6 DC HSM is also available in Sony Alpha mount.
Focal Range
Sigma 18-200mm f3.5-6.3 II DC OS HSM has a focal range of 18-200mm and
11.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-300mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-125mm F3.8-5.6 DC HSM has a focal range of 18-125mm and 6.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-187.5mm when used on a APS-C / DX format camera.
