The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax FA 50mm F1.4 Classic and the Sigma 50mm F1.4 DG HSM A 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 DG HSM A is the longer of the two lenses at 100mm. The Pentax FA 50mm F1.4 Classic with a length of 37mm, is 63mm shorter. Besides being longer, the Sigma 50mm F1.4 DG HSM A also has a larger diameter of 85mm compared to the Pentax FA 50mm F1.4 Classic's 65mm 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 FA 50mm F1.4 Classic weighs 216g, which means it is 599g (73%) lighter than the Sigma 50mm F1.4 DG HSM A which has a weight of 815g.
Filter Threads
The Pentax FA 50mm F1.4 Classic has a filter size of 49mm whereas the Sigma 50mm F1.4 DG HSM A has a 77mm 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 FA 50mm F1.4 Classic:
And these are the 77mm filters that we recommend for the Sigma 50mm F1.4 DG HSM A:
Lens Mounts
The Pentax FA 50mm F1.4 Classic has the Pentax KAF lens mount whereas the Sigma 50mm F1.4 DG HSM A has the Sony Alpha lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and Sony A99 II, Sony A68 and Sony A77 II for the Sony Alpha Mount.
Sigma 50mm F1.4 DG HSM A is also available in Canon EF , Sigma SA, Nikon F (FX) and Leica L mounts.
Focal Range
Both lenses have the same focal range of
50mm and the fastest aperture of
F1.4.
