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 Canon 55-250mm f4-5.6 IS STM 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 55-250mm f4-5.6 IS STM is the longer of the two lenses at 111mm. The Sigma 18-200mm F3.5-6.3 DC with a length of 78mm, is 33mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 70mm.
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. Canon 55-250mm f4-5.6 IS STM weighs 375g, 7% (30g) lighter than the Sigma 18-200mm F3.5-6.3 DC's weight of 405g.
Filter Threads
The Sigma 18-200mm F3.5-6.3 DC has a filter size of 62mm whereas the Canon 55-250mm f4-5.6 IS STM has a 58mm 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 58mm filters that we recommend for the Canon 55-250mm f4-5.6 IS STM:
Lens Mounts
The Sigma 18-200mm F3.5-6.3 DC has the Canon EF lens mount whereas the Canon 55-250mm f4-5.6 IS STM has the Canon EF-S 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 Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S 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.
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 Canon 55-250mm f4-5.6 IS STM has a focal range of 55-250mm and 4.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 88-400mm when used on a APS-C / DX format camera.