The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-FA 31mm F1.8 Ltd and the Sigma 35mm F1.4 DG HSM 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 35mm F1.4 DG HSM is the longer of the two lenses at 94mm. The HD Pentax-FA 31mm F1.8 Ltd with a length of 69mm, is 25mm shorter. Besides being longer, the Sigma 35mm F1.4 DG HSM also has a larger diameter of 77mm compared to the HD Pentax-FA 31mm F1.8 Ltd's 65mm diameter.
Below you can find a scaled side-by-side image of HD Pentax-FA 31mm F1.8 Ltd and Sigma 35mm F1.4 DG HSM to get a better idea of how their sizes compare in real life.
Comparison image of the HD Pentax-FA 31mm F1.8 Ltd and the Sigma 35mm F1.4 DG HSM Size and Weight 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. HD Pentax-FA 31mm F1.8 Ltd weighs 341g, which means it is 324g (48%) lighter than the Sigma 35mm F1.4 DG HSM which has a weight of 665g.
Filter Threads
The HD Pentax-FA 31mm F1.8 Ltd has a filter size of 58mm whereas the Sigma 35mm F1.4 DG HSM has a 67mm 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 HD Pentax-FA 31mm F1.8 Ltd:
And these are the 67mm filters that we recommend for the Sigma 35mm F1.4 DG HSM:
Lens Mounts
The HD Pentax-FA 31mm F1.8 Ltd has the Pentax KAF lens mount whereas the Sigma 35mm F1.4 DG HSM has the Pentax KAF3 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
Canon EF , Sony Alpha , Sigma SA , Nikon F (FX) and Leica L mounts.
Focal Range
HD Pentax-FA 31mm F1.8 Ltd 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 Sigma 35mm F1.4 DG HSM 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 .
