The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F1.4 DG HSM A and the Sigma 24mm F1.8 EX DG 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 20mm F1.4 DG HSM A is the longer of the two lenses at 130mm. The Sigma 24mm F1.8 EX DG with a length of 83mm is 47mm shorter. Besides being longer, the Sigma 20mm F1.4 DG HSM A also has a larger diameter of 91mm compared to Sigma 24mm F1.8 EX DG's 84mm 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 24mm F1.8 EX DG weighs 485g, 48% (465g) lighter than the Sigma 20mm F1.4 DG HSM A's weight of 950g.
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 20mm F1.4 DG HSM A and Sigma 24mm F1.8 EX DG 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 20mm F1.4 DG HSM A is also available in Canon EF , Nikon F (FX) and Leica L mounts.
Sigma 24mm F1.8 EX DG is also available in Canon EF , Nikon F (FX), Four Thirds, Pentax KAF, Sony Alpha, Canon EF, Pentax KAF, Sony Alpha, Sigma SA and Nikon F (FX) mounts.
Focal Range
Sigma 20mm F1.4 DG HSM A is a prime lens with fixed focal lenght of 20mm. Sigma 24mm F1.8 EX DG is a prime lens with fixed focal lenght of 24mm.