The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 40mm F2.8 L 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 Pentax 40mm F2.8 L with a length of 15mm, is 79mm 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 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 40mm F2.8 L weighs 80g, which means it is 585g (87%) lighter than the Sigma 35mm F1.4 DG HSM which has a weight of 665g.
Filter Threads
The Pentax 40mm F2.8 L has a filter size of 49mm 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 49mm filters that we recommend you to consider for the Pentax 40mm F2.8 L:
And these are the 67mm filters that we recommend for the Sigma 35mm F1.4 DG HSM:
Lens Mounts
The Pentax 40mm F2.8 L 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 Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and , and for the Pentax KAF3 Mount.
Pentax 40mm F2.8 L is also available in 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
Pentax 40mm F2.8 L 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.
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.