The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 15mm f2.8 Fisheye and the Zeiss Milvus 18mm F2.8 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. Zeiss Milvus 18mm F2.8 is the longer of the two lenses at 93mm. The Canon 15mm f2.8 Fisheye with a length of 62mm, is 31mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 73mm.
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 15mm f2.8 Fisheye weighs 330g, which means it is 391g (54%) lighter than the Zeiss Milvus 18mm F2.8 which has a weight of 721g.
Below you can find the dimension and weight table of the Wideangle Fisheye Prime Lenses in Canon EF Mount for size comparison purposes.
Ultra-Wideangle Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Canon 15mm f2.8 Fisheye and the Zeiss Milvus 18mm F2.8 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.
Zeiss Milvus 18mm F2.8 is also available in Nikon F (FX) mount.
Focal Range
Canon 15mm f2.8 Fisheye is a prime lens with fixed focal lenght of 15mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
24mm.
On the other hand, the 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 1.6x crop, it provides a 35mm (FF) equivalent of 28.8mm.