The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 50mm f/1.8 STM and the Irix 45mm 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. Canon EF 50mm f/1.8 STM weighs 159g, which means it is 766g (82%) lighter than the Irix 45mm F1.4 which has a weight of 925g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Canon EF Mount for size comparison purposes.
Standard Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Canon EF 50mm f/1.8 STM has a filter size of 49mm whereas the Irix 45mm F1.4 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 Canon EF 50mm f/1.8 STM:
And these are the 77mm filters that we recommend for the Irix 45mm F1.4:
Lens Mounts
Both the Canon EF 50mm f/1.8 STM and the Irix 45mm F1.4 has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Irix 45mm F1.4 is also available in Nikon F (FX) and Pentax KAF2 mounts.
Focal Range
Canon EF 50mm f/1.8 STM 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.
On the other hand, the 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 1.6x crop, it provides a 35mm (FF) equivalent of 72mm.