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 DC and the Sigma 17-70mm F2.8-4 DC 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 17-70mm F2.8-4 DC OS HSM is the longer of the two lenses at 89mm. The Sigma 18-200mm F3.5-6.3 DC with a length of 78mm, is 11mm shorter. Besides being longer, the Sigma 17-70mm F2.8-4 DC OS HSM also has a larger diameter of 79mm compared to the Sigma 18-200mm F3.5-6.3 DC's 70mm 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. Sigma 18-200mm F3.5-6.3 DC weighs 405g, which means it is 115g (22%) lighter than the Sigma 17-70mm F2.8-4 DC OS HSM which has a weight of 520g.
Filter Threads
The Sigma 18-200mm F3.5-6.3 DC has a filter size of 62mm whereas the Sigma 17-70mm F2.8-4 DC OS HSM has a 72mm 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 Sigma 18-200mm F3.5-6.3 DC:
And these are the 72mm filters that we recommend for the Sigma 17-70mm F2.8-4 DC OS HSM:
Lens Mounts
The Sigma 18-200mm F3.5-6.3 DC has the Canon EF lens mount whereas the Sigma 17-70mm F2.8-4 DC OS HSM has the Sigma SA lens mount. Some of the latest released cameras that are compatible with these mounts are Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount and Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 18-200mm F3.5-6.3 DC is also available in the Nikon F (DX) , Pentax KAF, Sony Alpha and Sigma SA mounts.
Sigma 17-70mm F2.8-4 DC OS HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Focal Range
Sigma 18-200mm F3.5-6.3 DC has a focal range of 18-200mm and
11.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-320mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 17-70mm F2.8-4 DC OS HSM has a focal range of 17-70mm and 4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 25.5-105mm when used on a APS-C / DX format camera.
