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 Samyang 35mm F1.4 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. Samyang 35mm F1.4 is the longer of the two lenses at 112mm. The Pentax FA 31mm F1.8 L with a length of 69mm, is 43mm shorter. On the other hand, the Pentax FA 31mm F1.8 L has a larger diameter of 65mm compared to the Samyang 35mm F1.4's 63mm 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 31mm F1.8 L weighs 345g, which means it is 315g (47%) lighter than the Samyang 35mm F1.4 which has a weight of 660g.
Below you can find the dimension and weight table of the Wideangle Prime Lenses in Pentax KAF Mount for size comparison purposes.
Wideangle Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The Pentax FA 31mm F1.8 L has a filter size of 58mm whereas the Samyang 35mm F1.4 has a 77mm 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 Pentax FA 31mm F1.8 L:
And these are the 77mm filters that we recommend for the Samyang 35mm F1.4:
Lens Mounts
Both the Pentax FA 31mm F1.8 L and the Samyang 35mm F1.4 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.
Samyang 35mm F1.4 is also available in Canon EF , Nikon F (FX), Four Thirds, Sony Alpha, Sony E and Samsung NX mounts.
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 Samyang 35mm F1.4 is a prime lens with fixed focal lenght of 35mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 52.5mm.