The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Irix 11mm F4 and the Voigtlander 20mm F3.5 SL II for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Irix 11mm F4 is the longer of the two lenses at 118mm. The Voigtlander 20mm F3.5 SL II with a length of 29mm, is 89mm shorter. Besides being longer, the Irix 11mm F4 also has a larger diameter of 103mm compared to the Voigtlander 20mm F3.5 SL II's 63mm diameter.
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. Voigtlander 20mm F3.5 SL II weighs 205g, 74% (585g) lighter than the Irix 11mm F4's weight of 790g.
Lens Mounts
The Irix 11mm F4 has the Pentax KAF3 lens mount whereas the Voigtlander 20mm F3.5 SL II has the Pentax KAF 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 KAF3 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Irix 11mm F4 is also available in the Canon EF and Nikon F (FX) mounts.
Voigtlander 20mm F3.5 SL II is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Irix 11mm F4 is a prime lens with fixed focal lenght of 11mm.
On the other hand, the Voigtlander 20mm F3.5 SL II is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 30mm.
