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 Pentax 12-24mm F4.0 ED AL 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 12-24mm F4.0 ED AL is the longer of the two lenses at 84mm. The OM System 25mm F1.8 II with a length of 41mm, is 43mm shorter. Besides being longer, the Pentax 12-24mm F4.0 ED AL also has a larger diameter of 88mm 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 274g (63%) lighter than the Pentax 12-24mm F4.0 ED AL which has a weight of 430g.
Filter Threads
The OM System 25mm F1.8 II has a filter size of 46mm whereas the Pentax 12-24mm F4.0 ED AL 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 46mm filters that we recommend you to consider for the OM System 25mm F1.8 II:
And these are the 77mm filters that we recommend for the Pentax 12-24mm F4.0 ED AL:
Lens Mounts
The OM System 25mm F1.8 II has the Micro Four Thirds lens mount whereas the Pentax 12-24mm F4.0 ED AL has the Pentax KAF 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 KAF 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 Pentax 12-24mm F4.0 ED AL has a focal range of 12-24mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 18-36mm when used on a APS-C / DX format camera.
