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 40mm F2.8 XS Lens 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 40mm F2.8 XS Lens with a length of 9mm, is 85mm shorter. Besides being longer, the Sigma 35mm F1.4 DG HSM also has a larger diameter of 77mm compared to the Pentax 40mm F2.8 XS Lens'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 40mm F2.8 XS Lens weighs 45g, 93% (620g) lighter than the Sigma 35mm F1.4 DG HSM's weight of 665g.
Lens Mounts
The Sigma 35mm F1.4 DG HSM has the Pentax KAF3 lens mount whereas the Pentax 40mm F2.8 XS Lens 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 Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Sigma 35mm F1.4 DG HSM is also available in Canon EF , Sony Alpha, Sigma SA, Nikon F (FX) and Leica L mounts.
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 40mm F2.8 XS Lens is a prime lens with fixed focal lenght of 40mm which has an effective (full-frame 35mm equivalent) focal range of 60mm when used on a APS-C / DX format camera.