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 F4-5.6 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 F4-5.6 EX DC HSM with a length of 81mm, is 9mm 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 F4-5.6 EX DC HSM's 84mm 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 10-20mm F4-5.6 EX DC HSM weighs 470g, 9% (50g) lighter than the Sigma 20mm F1.8 EX DG RF's weight of 520g.
Filter Threads
The Sigma 20mm F1.8 EX DG RF has a filter size of 82mm whereas the Sigma 10-20mm F4-5.6 EX DC HSM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 82mm filters that we recommend you to consider for the Sigma 20mm F1.8 EX DG RF:
And these are the 77mm filters that we recommend for the Sigma 10-20mm F4-5.6 EX DC HSM:
Lens Mounts
Both the Sigma 20mm F1.8 EX DG RF and the Sigma 10-20mm F4-5.6 EX DC HSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Sigma 20mm F1.8 EX DG RF is also available in the Canon EF , Nikon F (DX), Pentax KAF and Sigma SA mounts.
Sigma 10-20mm F4-5.6 EX DC HSM is also available in Canon EF , Four Thirds, Pentax KAF, Sigma SA and Nikon F (DX) mounts.
Focal Range
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 1.5x crop, it provides a 35mm (FF) equivalent of
30mm.
On the other hand, the Sigma 10-20mm F4-5.6 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.
