The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Olympus 25mm F1.2 Pro and the Sigma 30mm F1.4 C for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Olympus 25mm F1.2 Pro is the longer of the two lenses at 87mm. The Sigma 30mm F1.4 C with a length of 73mm is 14mm shorter. Besides being longer, the Olympus 25mm F1.2 Pro also has a larger diameter of 70mm compared to Sigma 30mm F1.4 C's 65mm 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. Sigma 30mm F1.4 C weighs 265g, 35% (145g) lighter than the Olympus 25mm F1.2 Pro's weight of 410g.
Below you can find the dimension and weight table of the 'Standard Prime Lenses in Micro Four Thirds Mount for size comparison purposes.
Standard Prime Lenses in Micro Four Thirds Mount for Size Comparison
Lens Mounts
Both Olympus 25mm F1.2 Pro and Sigma 30mm F1.4 C has the same Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with the Micro Four Thirds lenses are OM System OM-5, Panasonic GH6 and OM System OM-1.
Sigma 30mm F1.4 C is also available in Sony E and Fujifilm X mounts.
Focal Range
Olympus 25mm F1.2 Pro is a prime lens with fixed focal lenght of 25mm which has an effective (full-frame 35mm equivalent) focal range of 50mm when used on a FourThirds format camera. 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.