The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 50mm F1.4 EX DG HSM and the Pentax 50mm F1.8 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 50mm F1.4 EX DG HSM is the longer of the two lenses at 68mm. The Pentax 50mm F1.8 with a length of 39mm, is 29mm shorter. Besides being longer, the Sigma 50mm F1.4 EX DG HSM also has a larger diameter of 85mm compared to the Pentax 50mm F1.8'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 50mm F1.8 weighs 122g, 75% (383g) lighter than the Sigma 50mm F1.4 EX DG HSM's weight of 505g.
Filter Threads
The Sigma 50mm F1.4 EX DG HSM has a filter size of 77mm whereas the Pentax 50mm F1.8 has a 52mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Sigma 50mm F1.4 EX DG HSM:
And these are the 52mm filters that we recommend for the Pentax 50mm F1.8:
Lens Mounts
The Sigma 50mm F1.4 EX DG HSM has the Pentax KAF3 lens mount whereas the Pentax 50mm F1.8 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 50mm F1.4 EX DG HSM is also available in Canon EF , Sony Alpha, Sigma SA, Nikon F (FX) and Four Thirds mounts.
Focal Range
Both lenses have the same focal range of
50mm but while Sigma 50mm F1.4 EX DG HSM has the fastest aperture of
F1.4, the Pentax 50mm F1.8's widest aperture value is
F1.8.