The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic 8-18mm F2.8-4.0 ASPH and the Olympus ED 9-18mm f4.0-5.6 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. Panasonic 8-18mm F2.8-4.0 ASPH is the longer of the two lenses at 88mm. The Olympus ED 9-18mm f4.0-5.6 with a length of 50mm, is 38mm shorter. Besides being longer, the Panasonic 8-18mm F2.8-4.0 ASPH also has a larger diameter of 73mm compared to the Olympus ED 9-18mm f4.0-5.6's 57mm 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 ED 9-18mm f4.0-5.6 weighs 155g, 50% (160g) lighter than the Panasonic 8-18mm F2.8-4.0 ASPH's weight of 315g.
Below you can find the dimension and weight table of the Wideangle Zoom Lenses in Micro Four Thirds Mount for size comparison purposes.
Ultra-Wideangle Lenses in Micro Four Thirds Mount for Size Comparison
Filter Threads
The Panasonic 8-18mm F2.8-4.0 ASPH has a filter size of 67mm whereas the Olympus ED 9-18mm f4.0-5.6 has a 52mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Panasonic 8-18mm F2.8-4.0 ASPH:
And these are the 52mm filters that we recommend for the Olympus ED 9-18mm f4.0-5.6:
Lens Mounts
Both the Panasonic 8-18mm F2.8-4.0 ASPH and the Olympus ED 9-18mm f4.0-5.6 has the same Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with the Micro Four Thirds lenses are OM System OM-1 II, Panasonic G9 II and OM System OM-5.
Olympus ED 9-18mm f4.0-5.6 is also available in Four Thirds mount.
Focal Range
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.
On the other hand, the Olympus ED 9-18mm f4.0-5.6 has a focal range of 9-18mm and 2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 18-36mm when used on a FourThirds format camera.