The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 35mm F1.4 DG HSM and the Pentax 21mm F3.2 AL L 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 Pentax 21mm F3.2 AL L with a length of 25mm, is 69mm shorter. Besides being longer, the Sigma 35mm F1.4 DG HSM also has a larger diameter of 77mm compared to the Pentax 21mm F3.2 AL L'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 21mm F3.2 AL L weighs 134g, 79% (531g) lighter than the Sigma 35mm F1.4 DG HSM's weight of 665g.
Filter Threads
The Sigma 35mm F1.4 DG HSM has a filter size of 67mm whereas the Pentax 21mm F3.2 AL L has a 49mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Sigma 35mm F1.4 DG HSM:
And these are the 49mm filters that we recommend for the Pentax 21mm F3.2 AL L:
Lens Mounts
The Sigma 35mm F1.4 DG HSM has the Pentax KAF3 lens mount whereas the Pentax 21mm F3.2 AL L has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are , and for the Pentax KAF3 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Sigma 35mm F1.4 DG HSM is also available in the Canon EF , Sony Alpha, Sigma SA, Nikon F (FX) and Leica L mounts.
Pentax 21mm F3.2 AL L is also available in Pentax KAF mount.
Focal Range
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.
On the other hand, the Pentax 21mm F3.2 AL L is a prime lens with fixed focal lenght of 21mm which has an effective (full-frame 35mm equivalent) focal range of 31.5mm when used on a APS-C / DX format camera.
