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 OS HSM and the Sigma 18-125mm F3.8-5.6 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 18-200mm F3.5-6.3 DC OS HSM is the longer of the two lenses at 98mm. The Sigma 18-125mm F3.8-5.6 DC OS HSM with a length of 89mm, is 9mm shorter. Besides being longer, the Sigma 18-200mm F3.5-6.3 DC OS HSM also has a larger diameter of 79mm compared to the Sigma 18-125mm F3.8-5.6 DC OS 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. Sigma 18-125mm F3.8-5.6 DC OS HSM weighs 490g, 18% (110g) lighter than the Sigma 18-200mm F3.5-6.3 DC OS HSM's weight of 600g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Sigma SA Mount for size comparison purposes.
Superzoom Lenses in Sigma SA Mount for Size Comparison
Filter Threads
The Sigma 18-200mm F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Sigma 18-125mm F3.8-5.6 DC OS HSM has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sigma 18-200mm F3.5-6.3 DC OS HSM:
And these are the 67mm filters that we recommend for the Sigma 18-125mm F3.8-5.6 DC OS HSM:
Lens Mounts
Both the Sigma 18-200mm F3.5-6.3 DC OS HSM and the Sigma 18-125mm F3.8-5.6 DC OS HSM has the same Sigma SA lens mount. Some of the latest released cameras that are compatible with the Sigma SA lenses are Sigma SD1 Merrill, Sigma SD1 and .
Sigma 18-200mm F3.5-6.3 DC OS HSM is also available in Canon EF and Nikon F (DX) mounts.
Sigma 18-125mm F3.8-5.6 DC OS HSM is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Sigma 18-200mm F3.5-6.3 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 OS 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.