The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Zeiss Batis 18mm F2.8 and the ZEISS Loxia 21mm F2.8 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 Batis 18mm F2.8 is the longer of the two lenses at 80mm. The ZEISS Loxia 21mm F2.8 with a length of 72mm is 8mm shorter. Besides being longer, the Zeiss Batis 18mm F2.8 also has a larger diameter of 78mm compared to ZEISS Loxia 21mm F2.8's 62mm 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 Batis 18mm F2.8 weighs 330g, which means it is 64g (16%) lighter than the ZEISS Loxia 21mm F2.8 which has a weight of 394g.
Below you can find the dimension and weight table of the 'Wideangle Prime Lenses in Sony E Mount for size comparison purposes.
Wideangle Prime Lenses in Sony E Mount for Size Comparison
Lens Mounts
Both Zeiss Batis 18mm F2.8 and ZEISS Loxia 21mm F2.8 has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A7R V, Sony FX30 and Sony A7 IV.
Focal Range
Zeiss Batis 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.
ZEISS Loxia 21mm F2.8 is a prime lens with fixed focal lenght of 21mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 31.5mm.