The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Zeiss Otus 100mm F1.4 and the Canon 85mm f1.8 USM for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Zeiss Otus 100mm F1.4 is the longer of the two lenses at 129mm. The Canon 85mm f1.8 USM with a length of 72mm is 57mm shorter. Besides being longer, the Zeiss Otus 100mm F1.4 also has a larger diameter of 101mm compared to Canon 85mm f1.8 USM's 75mm 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. Canon 85mm f1.8 USM weighs 425g, 69% (980g) lighter than the Zeiss Otus 100mm F1.4's weight of 1405g.
Below you can find the dimension and weight table of the 'Telephoto Prime Lenses in Canon EF Mount for size comparison purposes.
Telephoto Prime Lenses in Canon EF Mount for Size Comparison
Both Zeiss Otus 100mm F1.4 and Canon 85mm f1.8 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 100mm F1.4 is also available in Nikon F (FX) mount.
Zeiss Otus 100mm F1.4 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 an 35mm (FF) equivalent of 160mm.
Canon 85mm f1.8 USM 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 an 35mm (FF) equivalent of 136mm.