The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Panasonic 9mm F1.7 ASPH and the Samyang 12mm f2.0 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. Samyang 12mm f2.0 is the longer of the two lenses at 59mm. The Panasonic 9mm F1.7 ASPH with a length of 52mm, is 7mm shorter. Besides being longer, the Samyang 12mm f2.0 also has a larger diameter of 73mm compared to the Panasonic 9mm F1.7 ASPH's 61mm 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 9mm F1.7 ASPH weighs 130g, which means it is 130g (50%) lighter than the Samyang 12mm f2.0 which has a weight of 260g.
Filter Threads
The Panasonic 9mm F1.7 ASPH has a filter size of 55mm whereas the Samyang 12mm f2.0 has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 55mm filters that we recommend you to consider for the Panasonic 9mm F1.7 ASPH:
And these are the 67mm filters that we recommend for the Samyang 12mm f2.0:
Lens Mounts
Both the Panasonic 9mm F1.7 ASPH and the Samyang 12mm f2.0 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.
Samyang 12mm f2.0 is also available in Canon EF-M , Fujifilm X, Sony E and Samsung NX mounts.
Focal Range
Panasonic 9mm F1.7 ASPH is a prime lens with fixed focal lenght of 9mm which has an effective (full-frame 35mm equivalent) focal range of
18mm when used on a FourThirds format camera.
On the other hand, the Samyang 12mm f2.0 is a prime lens with fixed focal lenght of 12mm which has an effective (full-frame 35mm equivalent) focal range of 18mm when used on a APS-C / DX format camera.