The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 24-70mm F2.8 GM and the Samyang 20mm F1.8 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. Sony FE 24-70mm F2.8 GM is the longer of the two lenses at 136mm. The Samyang 20mm F1.8 with a length of 88mm, is 48mm shorter. Besides being longer, the Sony FE 24-70mm F2.8 GM also has a larger diameter of 88mm compared to the Samyang 20mm F1.8's 83mm 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. Samyang 20mm F1.8 weighs 497g, 43% (389g) lighter than the Sony FE 24-70mm F2.8 GM's weight of 886g.
Filter Threads
The Sony FE 24-70mm F2.8 GM has a filter size of 82mm whereas the Samyang 20mm F1.8 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 Sony FE 24-70mm F2.8 GM:
And these are the 77mm filters that we recommend for the Samyang 20mm F1.8:
Lens Mounts
Both the Sony FE 24-70mm F2.8 GM and the Samyang 20mm F1.8 has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Samyang 20mm F1.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Micro Four Thirds, Nikon F (FX), Pentax KAF, Samsung NX and Sony Alpha mounts.
Focal Range
Sony FE 24-70mm F2.8 GM has a focal range of 24-70mm and
2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
36 - 105mm.
On the other hand, the 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 1.5x crop, it provides a 35mm (FF) equivalent of 30mm.