The type of photography that you are planning to use is an important decision factor. Here we have evaluated the OM System 25mm F1.8 II and the PENTAX15-30mm F2.8 ED 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. PENTAX15-30mm F2.8 ED WR is the longer of the two lenses at 144mm. The OM System 25mm F1.8 II with a length of 41mm, is 103mm shorter. Besides being longer, the PENTAX15-30mm F2.8 ED WR also has a larger diameter of 99mm compared to the OM System 25mm F1.8 II's 56mm 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. OM System 25mm F1.8 II weighs 156g, which means it is 884g (85%) lighter than the PENTAX15-30mm F2.8 ED WR which has a weight of 1040g.
Lens Mounts
The OM System 25mm F1.8 II has the Micro Four Thirds lens mount whereas the PENTAX15-30mm F2.8 ED WR has the Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with these mounts are OM System OM-3 Astro, OM System OM-5 II and OM System OM-3 for the Micro Four Thirds Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount.
Focal Range
OM System 25mm F1.8 II is a prime lens with fixed focal lenght of 25mm which has an effective (full-frame 35mm equivalent) focal range of
50mm when used on a FourThirds format camera.
On the other hand, the PENTAX15-30mm F2.8 ED WR has a focal range of 15-30mm and 2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 22.5 - 45mm.
