The type of photography that you are planning to use is an important decision factor. Here we have evaluated the OM SYSTEM 9-18mm f4.0-5.6 II and the Samyang 10mm f2.8 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 10mm f2.8 is the longer of the two lenses at 77mm. The OM SYSTEM 9-18mm f4.0-5.6 II with a length of 49mm, is 28mm shorter. Besides being longer, the Samyang 10mm f2.8 also has a larger diameter of 86mm compared to the OM SYSTEM 9-18mm f4.0-5.6 II's 56mm 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. OM SYSTEM 9-18mm f4.0-5.6 II weighs 154g, which means it is 426g (73%) lighter than the Samyang 10mm f2.8 which has a weight of 580g.
Lens Mounts
Both the OM SYSTEM 9-18mm f4.0-5.6 II and the Samyang 10mm f2.8 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 10mm f2.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Nikon F (DX) and Four Thirds mounts.
Focal Range
OM SYSTEM 9-18mm f4.0-5.6 II 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.
On the other hand, the Samyang 10mm f2.8 is a prime lens with fixed focal lenght of 10mm which has an effective (full-frame 35mm equivalent) focal range of 15mm when used on a APS-C / DX format camera.