The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF-S 18-45mm f4.5-6.3 IS and the Sigma 18-50mm F2.8-4.5 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 18-50mm F2.8-4.5 DC OS HSM is the longer of the two lenses at 89mm. The Canon RF-S 18-45mm f4.5-6.3 IS with a length of 44mm, is 45mm shorter. Besides being longer, the Sigma 18-50mm F2.8-4.5 DC OS HSM also has a larger diameter of 74mm compared to the Canon RF-S 18-45mm f4.5-6.3 IS's 69mm 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 RF-S 18-45mm f4.5-6.3 IS weighs 130g, which means it is 265g (67%) lighter than the Sigma 18-50mm F2.8-4.5 DC OS HSM which has a weight of 395g.
Filter Threads
The Canon RF-S 18-45mm f4.5-6.3 IS has a filter size of 49mm whereas the Sigma 18-50mm F2.8-4.5 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 49mm filters that we recommend you to consider for the Canon RF-S 18-45mm f4.5-6.3 IS:
And these are the 67mm filters that we recommend for the Sigma 18-50mm F2.8-4.5 DC OS HSM:
Lens Mounts
The Canon RF-S 18-45mm f4.5-6.3 IS has the Canon RF lens mount whereas the Sigma 18-50mm F2.8-4.5 DC OS HSM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Canon R50 V, Canon R100 and Canon R50 for the Canon RF Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount.
Sigma 18-50mm F2.8-4.5 DC OS HSM is also available in Pentax KAF3 , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Canon RF-S 18-45mm f4.5-6.3 IS has a focal range of 18-45mm and
2.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-72mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-50mm F2.8-4.5 DC OS HSM has a focal range of 18-50mm and 2.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-80mm when used on a APS-C / DX format camera.
