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 Carl Zeiss Distagon T3,5/18 for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Samyang 20mm F1.8 is the longer of the two lenses at 88mm. The Carl Zeiss Distagon T3,5/18 with a length of 84mm is 4mm shorter. On the other hand, the Carl Zeiss Distagon T3,5/18 has a larger diameter of 87mm compared to Samyang 20mm F1.8's 83mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Carl Zeiss Distagon T3,5/18 weighs 470g, 5% (27g) lighter than the Samyang 20mm F1.8's weight of 497g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Canon EF Mount for size comparison purposes.
Wideangle Prime Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both Samyang 20mm F1.8 and Carl Zeiss Distagon T3,5/18 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 20mm F1.8 is also available in Canon EF-M , Fujifilm X, Micro Four Thirds, Nikon F (FX), Pentax KAF, Samsung NX, Sony Alpha and Sony E mounts.
Carl Zeiss Distagon T3,5/18 is also available in Pentax KAF and Nikon F (FX) 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 an 35mm (FF) equivalent of 32mm.
Carl Zeiss Distagon T3,5/18 is a prime lens with fixed focal lenght of 18mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 28.8mm.