The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Zeiss Loxia 25mm F2.4 and the Sigma 30mm F2.8 DN 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 Loxia 25mm F2.4 is the longer of the two lenses at 75mm. The Sigma 30mm F2.8 DN with a length of 41mm, is 34mm shorter. Besides being longer, the Zeiss Loxia 25mm F2.4 also has a larger diameter of 62mm compared to the Sigma 30mm F2.8 DN's 61mm diameter.
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. Sigma 30mm F2.8 DN weighs 135g, 65% (258g) lighter than the Zeiss Loxia 25mm F2.4's weight of 393g.
Lens Mounts
Both the Zeiss Loxia 25mm F2.4 and the Sigma 30mm F2.8 DN has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony A9 III, Sony A7C Mark II and Sony A7CR.
Sigma 30mm F2.8 DN is also available in Micro Four Thirds mount.
Focal Range
Zeiss Loxia 25mm F2.4 is a prime lens with fixed focal lenght of 25mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
37.5mm.
On the other hand, the Sigma 30mm F2.8 DN is a prime lens with fixed focal lenght of 30mm which has an effective (full-frame 35mm equivalent) focal range of 45mm when used on a APS-C / DX format camera.