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 Samyang 35mm F1.4 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. Samyang 35mm F1.4 weighs 660g, 28% (265g) lighter than the Irix 45mm F1.4's weight of 925g.
Filter Threads
Both the Irix 45mm F1.4 and the Samyang 35mm F1.4 have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Irix 45mm F1.4 has the Pentax KAF2 lens mount whereas the Samyang 35mm F1.4 has the Sony E 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 Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount.
Irix 45mm F1.4 is also available in the Canon EF and Nikon F (FX) mounts.
Samyang 35mm F1.4 is also available in Canon EF , Nikon F (FX), Four Thirds, Pentax KAF, Sony Alpha and Samsung NX 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 Samyang 35mm F1.4 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.
