The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Irix 45mm F1.4 and the HD Pentax-D FA 50mm F1.4 SDM AW for their suitability to various photography scenarios:
Size and Weight Comparison
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-D FA 50mm F1.4 SDM AW weighs 910g, 1% (15g) lighter than the Irix 45mm F1.4's weight of 925g.
Lens Mounts
The Irix 45mm F1.4 has the Pentax KAF2 lens mount whereas the HD Pentax-D FA 50mm F1.4 SDM AW has the Pentax KAF3 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 KAF2 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount.
Irix 45mm F1.4 is also available in the Canon EF and Nikon F (FX) mounts.
Focal Range
Irix 45mm F1.4 is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
67.5mm.
On the other hand, the HD Pentax-D FA 50mm F1.4 SDM AW is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 75mm.
