The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 40mm F2.8 XS Lens and the Pentax 18-55mm F3.5-5.6 AL WR 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 18-55mm F3.5-5.6 AL WR is the longer of the two lenses at 68mm. The Pentax 40mm F2.8 XS Lens with a length of 9mm, is 59mm shorter. Besides being longer, the Pentax 18-55mm F3.5-5.6 AL WR also has a larger diameter of 69mm compared to the Pentax 40mm F2.8 XS Lens'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. Pentax 40mm F2.8 XS Lens weighs 45g, which means it is 185g (80%) lighter than the Pentax 18-55mm F3.5-5.6 AL WR which has a weight of 230g.
Lens Mounts
Both the Pentax 40mm F2.8 XS Lens and the Pentax 18-55mm F3.5-5.6 AL WR 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 Mono, Pentax KF and Pentax K-3 III.
Focal Range
Pentax 40mm F2.8 XS Lens is a prime lens with fixed focal lenght of 40mm which has an effective (full-frame 35mm equivalent) focal range of
60mm when used on a APS-C / DX format camera.
On the other hand, the Pentax 18-55mm F3.5-5.6 AL WR has a focal range of 18-55mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-82.5mm when used on a APS-C / DX format camera.
