The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 20mm F1.8 EX DG RF and the Sigma 8-16mm F4.5-5.6 DC 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 8-16mm F4.5-5.6 DC HSM is the longer of the two lenses at 106mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm, is 16mm shorter. On the other hand, the Sigma 20mm F1.8 EX DG RF has a larger diameter of 89mm compared to the Sigma 8-16mm F4.5-5.6 DC HSM's 75mm 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. Sigma 20mm F1.8 EX DG RF weighs 520g, which means it is 35g (6%) lighter than the Sigma 8-16mm F4.5-5.6 DC HSM which has a weight of 555g.
Lens Mounts
Both the Sigma 20mm F1.8 EX DG RF and the Sigma 8-16mm F4.5-5.6 DC HSM 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 F1.8 EX DG RF is also available in the Canon EF , Nikon F (DX), Pentax KAF and Sony Alpha mounts.
Sigma 8-16mm F4.5-5.6 DC HSM is also available in Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Focal Range
Sigma 20mm F1.8 EX DG RF is a prime lens with fixed focal lenght of 20mm.
On the other hand, the Sigma 8-16mm F4.5-5.6 DC HSM has a focal range of 8-16mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 12-24mm when used on a APS-C / DX format camera.
