The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 70mm F2.4 AL L and the Olympus M 45mm f1.8 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. Olympus M 45mm f1.8 is the longer of the two lenses at 46mm. The Pentax 70mm F2.4 AL L with a length of 26mm, is 20mm shorter. On the other hand, the Pentax 70mm F2.4 AL L has a larger diameter of 63mm compared to the Olympus M 45mm f1.8'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. Olympus M 45mm f1.8 weighs 116g, 10% (14g) lighter than the Pentax 70mm F2.4 AL L's weight of 130g.
Filter Threads
The Pentax 70mm F2.4 AL L has a filter size of 49mm whereas the Olympus M 45mm f1.8 has a 37mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 49mm filters that we recommend you to consider for the Pentax 70mm F2.4 AL L:
And these are the 37mm filters that we recommend for the Olympus M 45mm f1.8:
Lens Mounts
The Pentax 70mm F2.4 AL L has the Pentax KAF lens mount whereas the Olympus M 45mm f1.8 has the Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount and OM System OM-3 Astro, OM System OM-5 II and OM System OM-3 for the Micro Four Thirds Mount.
Pentax 70mm F2.4 AL L is also available in the Pentax KAF mount.
Focal Range
Pentax 70mm F2.4 AL L is a prime lens with fixed focal lenght of 70mm which has an effective (full-frame 35mm equivalent) focal range of
105mm when used on a APS-C / DX format camera.
On the other hand, the Olympus M 45mm f1.8 is a prime lens with fixed focal lenght of 45mm which has an effective (full-frame 35mm equivalent) focal range of 90mm when used on a FourThirds format camera.
