The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic DG 12mm F1.4 and the Sigma 19mm F2.8 EX DN for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Panasonic DG 12mm F1.4 is the longer of the two lenses at 70mm. The Sigma 19mm F2.8 EX DN with a length of 46mm, is 24mm shorter. Besides being longer, the Panasonic DG 12mm F1.4 also has a larger diameter of 70mm compared to the Sigma 19mm F2.8 EX DN's 61mm diameter.
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 19mm F2.8 EX DN weighs 140g, 58% (195g) lighter than the Panasonic DG 12mm F1.4's weight of 335g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Micro Four Thirds Mount for size comparison purposes.
Wideangle Prime Lenses in Micro Four Thirds Mount for Size Comparison
Lens Mounts
Both the Panasonic DG 12mm F1.4 and the Sigma 19mm F2.8 EX DN 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 19mm F2.8 EX DN is also available in Sony E mount.
Focal Range
Panasonic DG 12mm F1.4 is a prime lens with fixed focal lenght of 12mm which has an effective (full-frame 35mm equivalent) focal range of 24mm when used on a FourThirds format camera. Sigma 19mm F2.8 EX DN is a prime lens with fixed focal lenght of 19mm which has an effective (full-frame 35mm equivalent) focal range of 28.5mm when used on a APS-C / DX format camera.