The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 14mm F1.8 DG HSM and the Sigma 20mm F1.8 EX DG RF for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Sigma 14mm F1.8 DG HSM is the longer of the two lenses at 126mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm is 36mm shorter. Besides being longer, the Sigma 14mm F1.8 DG HSM also has a larger diameter of 95mm compared to Sigma 20mm F1.8 EX DG RF's 89mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sigma 20mm F1.8 EX DG RF weighs 520g, 55% (650g) lighter than the Sigma 14mm F1.8 DG HSM's weight of 1170g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Sigma SA Mount for size comparison purposes.
Wideangle Prime Lenses in Sigma SA Mount for Size Comparison
Lens Mounts
Both Sigma 14mm F1.8 DG HSM and Sigma 20mm F1.8 EX DG RF has the same Sigma SA lens mount. Some of the latest released cameras that are compatible with the Sigma SA lenses are Sigma Quattro, Sigma Quattro H and Sigma SD1 Merrill.
Sigma 14mm F1.8 DG HSM is also available in Nikon F (FX) and Canon EF mounts.
Sigma 20mm F1.8 EX DG RF is also available in Canon EF , Nikon F (DX), Pentax KAF and Sony Alpha mounts.
Focal Range
Sigma 14mm F1.8 DG HSM is a prime lens with fixed focal lenght of 14mm. Sigma 20mm F1.8 EX DG RF is a prime lens with fixed focal lenght of 20mm.