The type of photography that you are planning to use is an important decision factor. Here we have evaluated the HD Pentax-FA 35mm F2 AL and the Sigma 30mm F1.4 EX DC 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 30mm F1.4 EX DC HSM is the longer of the two lenses at 59mm. The HD Pentax-FA 35mm F2 AL with a length of 45mm, is 14mm shorter. Besides being longer, the Sigma 30mm F1.4 EX DC HSM also has a larger diameter of 77mm compared to the HD Pentax-FA 35mm F2 AL's 64mm 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. HD Pentax-FA 35mm F2 AL weighs 193g, which means it is 237g (55%) lighter than the Sigma 30mm F1.4 EX DC HSM which has a weight of 430g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Pentax KAF Mount for size comparison purposes.
Standard Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The HD Pentax-FA 35mm F2 AL has a filter size of 49mm whereas the Sigma 30mm F1.4 EX DC HSM has a 62mm 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 HD Pentax-FA 35mm F2 AL:
And these are the 62mm filters that we recommend for the Sigma 30mm F1.4 EX DC HSM:
Lens Mounts
Both the HD Pentax-FA 35mm F2 AL and the Sigma 30mm F1.4 EX DC HSM 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.
Sigma 30mm F1.4 EX DC HSM is also available in Canon EF-S , Nikon F (DX), Four Thirds, Sony Alpha and Sigma SA mounts.
Focal Range
HD Pentax-FA 35mm F2 AL is a prime lens with fixed focal lenght of 35mm which has an effective (full-frame 35mm equivalent) focal range of
52.5mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 30mm F1.4 EX DC HSM is a prime lens with fixed focal lenght of 30mm which has an effective (full-frame 35mm equivalent) focal range of 45mm when used on a APS-C / DX format camera.