The type of photography that you are planning to use is an important decision factor. Here we have evaluated the PENTAX28-105mm F3.5-5.6 WR and the Pentax 18-135mm F3.5-5.6ED 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. PENTAX28-105mm F3.5-5.6 WR is the longer of the two lenses at 87mm. The Pentax 18-135mm F3.5-5.6ED with a length of 76mm, is 11mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 73mm.
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 18-135mm F3.5-5.6ED weighs 405g, 7% (35g) lighter than the PENTAX28-105mm F3.5-5.6 WR's weight of 440g.
Filter Threads
Both the PENTAX28-105mm F3.5-5.6 WR and the Pentax 18-135mm F3.5-5.6ED have the same Filter thread size of 62mm.
Below are links to the 62mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the PENTAX28-105mm F3.5-5.6 WR and the Pentax 18-135mm F3.5-5.6ED has the same Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with the Pentax KAF3 lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Focal Range
PENTAX28-105mm F3.5-5.6 WR has a focal range of 28-105mm and
3.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 157.5mm.
On the other hand, the Pentax 18-135mm F3.5-5.6ED has a focal range of 18-135mm and 7.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-202.5mm when used on a APS-C / DX format camera.
