The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-50mm f2.8 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
The size of a lens is a crucial factor to consider 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 17-50mm f2.8 XR II LD with a length of 82mm, is 4mm shorter. On the other hand, the Tamron 17-50mm f2.8 XR II LD has a larger diameter of 74mm compared to the Sigma 18-200mm F3.5-6.3 DC OS HSM C's 71mm 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
The Tamron 17-50mm f2.8 XR II LD has a filter size of 67mm whereas the Sigma 18-200mm F3.5-6.3 DC OS HSM C has a 62mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Tamron 17-50mm f2.8 XR II LD:
And these are the 62mm filters that we recommend for the Sigma 18-200mm F3.5-6.3 DC OS HSM C:
Lens Mounts
The Tamron 17-50mm f2.8 XR II LD has the Pentax KAF lens mount whereas the Sigma 18-200mm F3.5-6.3 DC OS HSM C has the Nikon F (DX) 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 KAF Mount and Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount.
Tamron 17-50mm f2.8 XR II LD is also available in the 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 , Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Tamron 17-50mm f2.8 XR II LD 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 Sigma 18-200mm F3.5-6.3 DC OS HSM C 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.
