The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-300 F3.5-6.3 DC OS HSM and the Canon 55-250mm f4-5.6 IS 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 is the longer of the two lenses at 108mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 6mm shorter. On the other hand, the Sigma 18-300 F3.5-6.3 DC OS HSM has a larger diameter of 79mm compared to the Canon 55-250mm f4-5.6 IS'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. Canon 55-250mm f4-5.6 IS weighs 390g, 33% (195g) lighter than the Sigma 18-300 F3.5-6.3 DC OS HSM's weight of 585g.
Filter Threads
The Sigma 18-300 F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Canon 55-250mm f4-5.6 IS 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 72mm filters that we recommend you to consider for the Sigma 18-300 F3.5-6.3 DC OS HSM:
And these are the 58mm filters that we recommend for the Canon 55-250mm f4-5.6 IS:
Lens Mounts
The Sigma 18-300 F3.5-6.3 DC OS HSM has the Canon EF lens mount whereas the Canon 55-250mm f4-5.6 IS 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 18-300 F3.5-6.3 DC OS HSM is also available in Nikon F (DX) , Pentax KAF3, Sigma SA and Sony Alpha mounts.
Focal Range
Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and
16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-480mm when used on a APS-C / DX format camera.
On the other hand, the Canon 55-250mm f4-5.6 IS 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.