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 10-20mm F3.5 EX 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 20mm F1.8 EX DG RF is the longer of the two lenses at 90mm. The Sigma 10-20mm F3.5 EX DC HSM with a length of 88mm, is 2mm shorter. Besides being longer, the Sigma 20mm F1.8 EX DG RF also has a larger diameter of 89mm compared to the Sigma 10-20mm F3.5 EX DC HSM's 87mm 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.
Filter Threads
Both the Sigma 20mm F1.8 EX DG RF and the Sigma 10-20mm F3.5 EX DC HSM have the same Filter thread size of 82mm.
Below are links to the 82mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Sigma 20mm F1.8 EX DG RF and the Sigma 10-20mm F3.5 EX 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 10-20mm F3.5 EX 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 10-20mm F3.5 EX DC HSM has a focal range of 10-20mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 15-30mm when used on a APS-C / DX format camera.
