The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 28-300mm f3.5-5.6L IS USM and the Sigma 18-200mm f3.5-6.3 II 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. Canon 28-300mm f3.5-5.6L IS USM is the longer of the two lenses at 184mm. The Sigma 18-200mm f3.5-6.3 II DC OS HSM with a length of 88mm, is 96mm shorter. Besides being longer, the Canon 28-300mm f3.5-5.6L IS USM also has a larger diameter of 92mm compared to the Sigma 18-200mm f3.5-6.3 II DC OS HSM's 75mm 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 II DC OS HSM weighs 490g, 70% (1180g) lighter than the Canon 28-300mm f3.5-5.6L IS USM's weight of 1670g.
Below you can find the dimension and weight table of the SuperZoom Lenses in Canon EF Mount for size comparison purposes.
Superzoom Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Canon 28-300mm f3.5-5.6L IS USM has a filter size of 77mm whereas the Sigma 18-200mm f3.5-6.3 II DC OS HSM 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 77mm filters that we recommend you to consider for the Canon 28-300mm f3.5-5.6L IS USM:
And these are the 62mm filters that we recommend for the Sigma 18-200mm f3.5-6.3 II DC OS HSM:
Lens Mounts
Both the Canon 28-300mm f3.5-5.6L IS USM and the Sigma 18-200mm f3.5-6.3 II DC OS HSM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Sigma 18-200mm f3.5-6.3 II DC OS HSM is also available in Nikon F (DX) and Sigma SA mounts.
Focal Range
Canon 28-300mm f3.5-5.6L IS USM has a focal range of 28-300mm and
10.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
44.8 - 480mm.
On the other hand, the 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 28.8-320mm when used on a APS-C / DX format camera.