Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Zeiss Milvus 25mm F1.4 is the longer of the two lenses at 123mm. The Samyang T-S 24mm f3.5 with a length of 112mm is 11mm shorter. Besides being longer, the Zeiss Milvus 25mm F1.4 also has a larger diameter of 95mm compared to Samyang T-S 24mm f3.5's 86mm 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. Samyang T-S 24mm f3.5 weighs 680g, 80% (545g) lighter than the Zeiss Milvus 25mm F1.4's weight of 1225g.
Both Zeiss Milvus 25mm F1.4 and Samyang T-S 24mm f3.5 has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Zeiss Milvus 25mm F1.4 is also available in Canon EF mount.
Samyang T-S 24mm f3.5 is also available in Canon EF , Pentax KAF, Sony Alpha and Sony E mounts.
Zeiss Milvus 25mm F1.4 is a prime lens with fixed focal lenght of 25mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 37.5mm.
Samyang T-S 24mm f3.5 is a prime lens with fixed focal lenght of 24mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 36mm.