The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 20mm F1.8 and the Sigma 10-20mm F3.5 EX DC HSM for their suitability to various photography scenarios:
Size and Weight Comparison
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. Samyang 20mm F1.8 weighs 497g, which means it is 23g (4%) lighter than the Sigma 10-20mm F3.5 EX DC HSM which has a weight of 520g.
Filter Threads
The Samyang 20mm F1.8 has a filter size of 77mm whereas the Sigma 10-20mm F3.5 EX DC HSM has a 82mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Samyang 20mm F1.8:
And these are the 82mm filters that we recommend for the Sigma 10-20mm F3.5 EX DC HSM:
Lens Mounts
Both the Samyang 20mm F1.8 and the Sigma 10-20mm F3.5 EX DC HSM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Samyang 20mm F1.8 is also available in the Canon EF-M , Fujifilm X, Micro Four Thirds, Nikon F (FX), Pentax KAF, Samsung NX, Sony Alpha and Sony E mounts.
Sigma 10-20mm F3.5 EX DC HSM is also available in Pentax KAF3 , Sony Alpha, Sigma SA and Nikon F (DX) mounts.
Focal Range
Samyang 20mm F1.8 is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
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 16-32mm when used on a APS-C / DX format camera.
