The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Zeiss Otus 85mm F1.4 and the Canon 100mm f2.8 Macro USM for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Zeiss Otus 85mm F1.4 is the longer of the two lenses at 138mm. The Canon 100mm f2.8 Macro USM with a length of 119mm, is 19mm shorter. Besides being longer, the Zeiss Otus 85mm F1.4 also has a larger diameter of 101mm compared to the Canon 100mm f2.8 Macro USM's 79mm diameter.
The 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. Canon 100mm f2.8 Macro USM weighs 600g, 50% (600g) lighter than the Zeiss Otus 85mm F1.4's weight of 1200g.
Lens Mounts
Both the Zeiss Otus 85mm F1.4 and the Canon 100mm f2.8 Macro USM 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 Otus 85mm F1.4 is also available in Nikon F (FX) mount.
Focal Range
Zeiss Otus 85mm F1.4 is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 136mm.
Canon 100mm f2.8 Macro USM is a prime lens with fixed focal lenght of 100mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 160mm.