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 Rokinon 7.5mm f3.5 Fisheye 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. OM SYSTEM 9-18mm f4.0-5.6 II is the longer of the two lenses at 49mm. The Rokinon 7.5mm f3.5 Fisheye with a length of 48mm, is 1mm shorter. On the other hand, the Rokinon 7.5mm f3.5 Fisheye has a larger diameter of 60mm 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 43g (21%) lighter than the Rokinon 7.5mm f3.5 Fisheye which has a weight of 197g.
Lens Mounts
Both the OM SYSTEM 9-18mm f4.0-5.6 II and the Rokinon 7.5mm f3.5 Fisheye 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.
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 Rokinon 7.5mm f3.5 Fisheye is a prime lens with fixed focal lenght of 8mm which has an effective (full-frame 35mm equivalent) focal range of 16mm when used on a FourThirds format camera.
