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 Planar T1,4/50 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 Planar T1,4/50 weighs 350g, 62% (575g) lighter than the Irix 45mm F1.4's weight of 925g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Nikon F (FX) Mount for size comparison purposes.
Standard Lenses in Nikon F (FX) Mount for Size Comparison
Filter Threads
The Irix 45mm F1.4 has a filter size of 77mm whereas the Carl Zeiss Planar T1,4/50 has a 58mm 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 58mm filters that we recommend for the Carl Zeiss Planar T1,4/50:
Lens Mounts
Both the Irix 45mm F1.4 and the Carl Zeiss Planar T1,4/50 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 Planar T1,4/50 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 Planar T1,4/50 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.