The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Viltrox AF 28mm F1.8 Z and the HD Pentax-FA 31mm F1.8 Ltd 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. Viltrox AF 28mm F1.8 Z is the longer of the two lenses at 82mm. The HD Pentax-FA 31mm F1.8 Ltd with a length of 69mm, is 13mm shorter. Besides being longer, the Viltrox AF 28mm F1.8 Z also has a larger diameter of 70mm compared to the HD Pentax-FA 31mm F1.8 Ltd's 65mm 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. HD Pentax-FA 31mm F1.8 Ltd weighs 341g, 7% (26g) lighter than the Viltrox AF 28mm F1.8 Z's weight of 367g.
Filter Threads
The Viltrox AF 28mm F1.8 Z has a filter size of 55mm whereas the HD Pentax-FA 31mm F1.8 Ltd 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 55mm filters that we recommend you to consider for the Viltrox AF 28mm F1.8 Z:
And these are the 58mm filters that we recommend for the HD Pentax-FA 31mm F1.8 Ltd:
Lens Mounts
The Viltrox AF 28mm F1.8 Z has the Nikon Z lens mount whereas the HD Pentax-FA 31mm F1.8 Ltd has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon ZR, Nikon Z5 II and RED Komodo-X 6K Z for the Nikon Z Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Focal Range
Viltrox AF 28mm F1.8 Z is a prime lens with fixed focal lenght of 28mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42mm.
On the other hand, the HD Pentax-FA 31mm F1.8 Ltd is a prime lens with fixed focal lenght of 31mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 46.5mm.
