The type of photography that you are planning to use is an important decision factor. Here we have evaluated the OM ED 20mm F1.4 Pro 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 a crucial factor to consider when comparing two lenses. OM ED 20mm F1.4 Pro is the longer of the two lenses at 62mm. The Sigma 19mm F2.8 EX DN with a length of 46mm, is 16mm shorter. Besides being longer, the OM ED 20mm F1.4 Pro also has a larger diameter of 63mm compared to the Sigma 19mm F2.8 EX 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 19mm F2.8 EX DN weighs 140g, 43% (107g) lighter than the OM ED 20mm F1.4 Pro's weight of 247g.
Filter Threads
The OM ED 20mm F1.4 Pro has a filter size of 58mm whereas the Sigma 19mm F2.8 EX DN has a 46mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the OM ED 20mm F1.4 Pro:
And these are the 46mm filters that we recommend for the Sigma 19mm F2.8 EX DN:
Lens Mounts
Both the OM ED 20mm F1.4 Pro 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-1 II, Panasonic G9 II and OM System OM-5.
Sigma 19mm F2.8 EX DN is also available in Sony E mount.
Focal Range
OM ED 20mm F1.4 Pro is a prime lens with fixed focal lenght of 20mm which has an effective (full-frame 35mm equivalent) focal range of
40mm when used on a FourThirds format camera.
On the other hand, the 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.