The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Kamlan 55mm F1.2 and the Sigma 30mm F1.4 C for their suitability to various photography scenarios:
Size and Weight Comparison
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. Sigma 30mm F1.4 C weighs 265g, 62% (435g) lighter than the Kamlan 55mm F1.2's weight of 700g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Sony E Mount for size comparison purposes.
Standard Prime Lenses in Sony E Mount for Size Comparison
Lens Mounts
Both the Kamlan 55mm F1.2 and the Sigma 30mm F1.4 C has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony ZV-E1, Sony A7R V and Sony FX30.
Sigma 30mm F1.4 C is also available in Micro Four Thirds , Fujifilm X and Nikon Z mounts.
Focal Range
Kamlan 55mm F1.2 is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 75mm.
Sigma 30mm F1.4 C 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.