The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron AF 18-200mm f3.5-6.3 XR II LD and the Sigma 18-200mm F3.5-6.3 DC OS HSM C for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 18-200mm F3.5-6.3 DC OS HSM C is the longer of the two lenses at 86mm. The Tamron AF 18-200mm f3.5-6.3 XR II LD with a length of 84mm is 2mm shorter. On the other hand, the Tamron AF 18-200mm f3.5-6.3 XR II LD has a larger diameter of 74mm compared to Sigma 18-200mm F3.5-6.3 DC OS HSM C's 71mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Tamron AF 18-200mm f3.5-6.3 XR II LD weighs 398g, which means it is 32g (7%) lighter than the Sigma 18-200mm F3.5-6.3 DC OS HSM C which has a weight of 430g.
Lens Mounts
Both Tamron AF 18-200mm f3.5-6.3 XR II LD has the Pentax KAF lens mount whereas the Sigma 18-200mm F3.5-6.3 DC OS HSM C has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax KF, Pentax K-3 III and Pentax KP for the Pentax KAF Mount and , and for the Pentax KAF3 Mount.
Tamron AF 18-200mm f3.5-6.3 XR II LD is also available in Canon EF , Nikon F (DX) and Sony Alpha mounts.
Sigma 18-200mm F3.5-6.3 DC OS HSM C is also available in Canon EF , Nikon F (DX), Sony Alpha and Sigma SA mounts.
Focal Range
Both lenses have the same focal range of 18-200mm and the fastest aperture of F3.5 - F6.3.