The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax FA 43mm F1.9 L and the Sigma 50mm F2.8 EX DG Macro 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. Sigma 50mm F2.8 EX DG Macro is the longer of the two lenses at 67mm. The Pentax FA 43mm F1.9 L with a length of 27mm, is 40mm shorter. Besides being longer, the Sigma 50mm F2.8 EX DG Macro also has a larger diameter of 71mm compared to the Pentax FA 43mm F1.9 L's 64mm 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. Pentax FA 43mm F1.9 L weighs 155g, which means it is 165g (51%) lighter than the Sigma 50mm F2.8 EX DG Macro which has a weight of 320g.
Filter Threads
The Pentax FA 43mm F1.9 L has a filter size of 49mm whereas the Sigma 50mm F2.8 EX DG Macro has a 55mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 49mm filters that we recommend you to consider for the Pentax FA 43mm F1.9 L:
And these are the 55mm filters that we recommend for the Sigma 50mm F2.8 EX DG Macro:
Lens Mounts
Both the Pentax FA 43mm F1.9 L and the Sigma 50mm F2.8 EX DG Macro has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.
Sigma 50mm F2.8 EX DG Macro is also available in Canon EF , Sony Alpha, Sigma SA and Nikon F (FX) mounts.
Focal Range
Pentax FA 43mm F1.9 L is a prime lens with fixed focal lenght of 43mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
64.5mm.
On the other hand, the Sigma 50mm F2.8 EX DG Macro 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.