Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Zeiss Milvus 15mm F2.8 is the longer of the two lenses at 100mm. The Zeiss Milvus 18mm F2.8 with a length of 93mm is 7mm shorter. Besides being longer, the Zeiss Milvus 15mm F2.8 also has a larger diameter of 102mm compared to Zeiss Milvus 18mm F2.8's 73mm 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. Zeiss Milvus 18mm F2.8 weighs 721g, 31% (226g) lighter than the Zeiss Milvus 15mm F2.8's weight of 947g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Nikon F (FX) Mount for size comparison purposes.
Wideangle Prime Lenses in Nikon F (FX) Mount for Size Comparison
Lens Mounts
Both Zeiss Milvus 15mm F2.8 and Zeiss Milvus 18mm F2.8 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 15mm F2.8 is also available in Canon EF mount.
Zeiss Milvus 18mm F2.8 is also available in Canon EF mount.
Focal Range
Zeiss Milvus 15mm F2.8 is a prime lens with fixed focal lenght of 15mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 22.5mm.
Zeiss Milvus 18mm F2.8 is a prime lens with fixed focal lenght of 18mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 27mm.