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 Carl Zeiss Makro-Planar T2/50 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. Carl Zeiss Makro-Planar T2/50 weighs 530g, 42% (395g) lighter than the Irix 45mm F1.4's weight of 925g.
Filter Threads
The Irix 45mm F1.4 has a filter size of 77mm whereas the Carl Zeiss Makro-Planar T2/50 has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Irix 45mm F1.4:
And these are the 67mm filters that we recommend for the Carl Zeiss Makro-Planar T2/50:
Lens Mounts
Both the Irix 45mm F1.4 and the Carl Zeiss Makro-Planar T2/50 has the same Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (FX) lenses are Nikon D6, Nikon D780 and Nikon D3500.
Irix 45mm F1.4 is also available in Canon EF and Pentax KAF2 mounts.
Carl Zeiss Makro-Planar T2/50 is also available in Canon EF and Pentax KAF 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 Carl Zeiss Makro-Planar T2/50 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.