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 Sigma 50mm F1.4 EX DG HSM 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. Sigma 50mm F1.4 EX DG HSM weighs 505g, 45% (420g) lighter than the Irix 45mm F1.4's weight of 925g.
Filter Threads
Both the Irix 45mm F1.4 and the Sigma 50mm F1.4 EX DG HSM 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 Nikon F (FX) lens mount whereas the Sigma 50mm F1.4 EX DG HSM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
Irix 45mm F1.4 is also available in the Canon EF and Pentax KAF2 mounts.
Sigma 50mm F1.4 EX DG HSM is also available in Pentax KAF3 , Sony Alpha, Sigma SA, Nikon F (FX) and Four Thirds 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 Sigma 50mm F1.4 EX DG HSM is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 80mm.
