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 Samyang 20mm F1.8 for their suitability to various photography scenarios:
Size and Weight Comparison
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, which means it is 182g (36%) lighter than the Samyang 20mm F1.8 which has a weight of 497g.
Filter Threads
The Panasonic 8-18mm F2.8-4.0 ASPH has a filter size of 67mm whereas the Samyang 20mm F1.8 has a 77mm 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 77mm filters that we recommend for the Samyang 20mm F1.8:
Lens Mounts
Both the Panasonic 8-18mm F2.8-4.0 ASPH and the Samyang 20mm F1.8 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-3 Astro, OM System OM-5 II and OM System OM-3.
Samyang 20mm F1.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Nikon F (FX), Pentax KAF, Samsung NX, Sony Alpha and Sony E mounts.
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 Samyang 20mm F1.8 is a prime lens with fixed focal lenght of 20mm.
