The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 50mm F1.8 and the Voigtlander 40mm F2 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. Pentax 50mm F1.8 is the longer of the two lenses at 39mm. The Voigtlander 40mm F2 SL II with a length of 25mm, is 14mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 63mm.
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. Pentax 50mm F1.8 weighs 122g, which means it is 78g (39%) lighter than the Voigtlander 40mm F2 SL II which has a weight of 200g.
Below you can find the dimension and weight table of the Standard Prime Lenses in Pentax KAF Mount for size comparison purposes.
Standard Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
Both the Pentax 50mm F1.8 and the Voigtlander 40mm F2 SL II have the same Filter thread size of 52mm.
Below are links to the 52mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Pentax 50mm F1.8 and the Voigtlander 40mm F2 SL II 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 40mm F2 SL II is also available in Canon EF and Nikon F (FX) mounts.
Focal Range
Pentax 50mm F1.8 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.
On the other hand, the Voigtlander 40mm F2 SL II is a prime lens with fixed focal lenght of 40mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 60mm.