The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Voigtlander 20mm F3.5 SL II and the Rokinon 24mm 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. Voigtlander 20mm F3.5 SL II weighs 205g, which means it is 375g (64%) lighter than the Rokinon 24mm f1.4 which has a weight of 580g.
Filter Threads
The Voigtlander 20mm F3.5 SL II has a filter size of 52mm whereas the Rokinon 24mm 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 52mm filters that we recommend you to consider for the Voigtlander 20mm F3.5 SL II:
And these are the 77mm filters that we recommend for the Rokinon 24mm f1.4:
Lens Mounts
Both the Voigtlander 20mm F3.5 SL II and the Rokinon 24mm f1.4 has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.
Voigtlander 20mm F3.5 SL II is also available in Canon EF and Nikon F (FX) mounts.
Rokinon 24mm f1.4 is also available in Canon EF , Nikon F (FX), Four Thirds, Sony Alpha and Samsung NX mounts.
Focal Range
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.
On the other hand, the Rokinon 24mm f1.4 is a prime lens with fixed focal lenght of 24mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 36mm.