The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 20mm f2.8 USM and the Samyang 24mm f1.4 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. Canon 20mm f2.8 USM weighs 405g, which means it is 175g (30%) lighter than the Samyang 24mm f1.4 which has a weight of 580g.
Filter Threads
The Canon 20mm f2.8 USM has a filter size of 72mm whereas the Samyang 24mm f1.4 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 72mm filters that we recommend you to consider for the Canon 20mm f2.8 USM:
And these are the 77mm filters that we recommend for the Samyang 24mm f1.4:
Lens Mounts
Both the Canon 20mm f2.8 USM and the Samyang 24mm f1.4 has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Samyang 24mm f1.4 is also available in Nikon F (FX) , Four Thirds, Pentax KAF, Sony Alpha, Sony E and Samsung NX mounts.
Focal Range
Canon 20mm f2.8 USM 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 Samyang 24mm f1.4 is a prime lens with fixed focal lenght of 24mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 38.4mm.