The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax FA 31mm F1.8 L and the Canon 50mm f1.4 USM 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. Pentax FA 31mm F1.8 L is the longer of the two lenses at 69mm. The Canon 50mm f1.4 USM with a length of 51mm, is 18mm shorter. On the other hand, the Canon 50mm f1.4 USM has a larger diameter of 74mm compared to the Pentax FA 31mm F1.8 L's 65mm 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. Canon 50mm f1.4 USM weighs 290g, 15% (55g) lighter than the Pentax FA 31mm F1.8 L's weight of 345g.
Filter Threads
Both the Pentax FA 31mm F1.8 L and the Canon 50mm f1.4 USM have the same Filter thread size of 58mm.
Below are links to the 58mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Pentax FA 31mm F1.8 L has the Pentax KAF lens mount whereas the Canon 50mm f1.4 USM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Focal Range
Pentax FA 31mm F1.8 L is a prime lens with fixed focal lenght of 31mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
46.5mm.
On the other hand, the Canon 50mm f1.4 USM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 80mm.
