The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 17-70mm F4.0 AL SDM and the Panasonic 8-18mm F2.8-4.0 ASPH 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 17-70mm F4.0 AL SDM is the longer of the two lenses at 94mm. The Panasonic 8-18mm F2.8-4.0 ASPH with a length of 88mm, is 6mm shorter. Besides being longer, the Pentax 17-70mm F4.0 AL SDM also has a larger diameter of 75mm compared to the Panasonic 8-18mm F2.8-4.0 ASPH's 73mm 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. Panasonic 8-18mm F2.8-4.0 ASPH weighs 315g, 35% (170g) lighter than the Pentax 17-70mm F4.0 AL SDM's weight of 485g.
Filter Threads
Both the Pentax 17-70mm F4.0 AL SDM and the Panasonic 8-18mm F2.8-4.0 ASPH have the same Filter thread size of 67mm.
Below are links to the 67mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Pentax 17-70mm F4.0 AL SDM has the Pentax KAF3 lens mount whereas the Panasonic 8-18mm F2.8-4.0 ASPH has the Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with these mounts are , and for the Pentax KAF3 Mount and OM System OM-3 Astro, OM System OM-5 II and OM System OM-3 for the Micro Four Thirds Mount.
Focal Range
Pentax 17-70mm F4.0 AL SDM has a focal range of 17-70mm and
4.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
25.5-105mm when used on a APS-C / DX format camera.
On the other hand, the Panasonic 8-18mm F2.8-4.0 ASPH has a focal range of 8-18mm and 2.3X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 16-36mm when used on a FourThirds format camera.
