The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon RF 50mm F1.8 STM and the Sigma 20mm F1.8 EX DG RF 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 20mm F1.8 EX DG RF is the longer of the two lenses at 90mm. The Canon RF 50mm F1.8 STM with a length of 41mm, is 49mm shorter. Besides being longer, the Sigma 20mm F1.8 EX DG RF also has a larger diameter of 89mm compared to the Canon RF 50mm F1.8 STM'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 50mm F1.8 STM weighs 160g, which means it is 360g (69%) lighter than the Sigma 20mm F1.8 EX DG RF which has a weight of 520g.
Filter Threads
The Canon RF 50mm F1.8 STM has a filter size of 43mm whereas the Sigma 20mm F1.8 EX DG RF has a 82mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 43mm filters that we recommend you to consider for the Canon RF 50mm F1.8 STM:
And these are the 82mm filters that we recommend for the Sigma 20mm F1.8 EX DG RF:
Lens Mounts
The Canon RF 50mm F1.8 STM has the Canon RF lens mount whereas the Sigma 20mm F1.8 EX DG RF has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Canon R6 V, Canon R6 III and Canon C50 for the Canon RF Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Sigma 20mm F1.8 EX DG RF is also available in Nikon F (DX) , Pentax KAF, Sony Alpha and Sigma SA mounts.
Focal Range
Canon RF 50mm F1.8 STM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
80mm.
On the other hand, the Sigma 20mm F1.8 EX DG RF is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 32mm.
