The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 10-18mm F2.8 DC DN C and the Rokinon 8mm f2.8 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. Rokinon 8mm f2.8 Fisheye is the longer of the two lenses at 77mm. The Sigma 10-18mm F2.8 DC DN C with a length of 64mm, is 13mm shorter. Besides being longer, the Rokinon 8mm f2.8 Fisheye also has a larger diameter of 75mm compared to the Sigma 10-18mm F2.8 DC DN C's 72mm 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. Sigma 10-18mm F2.8 DC DN C weighs 250g, which means it is 193g (43%) lighter than the Rokinon 8mm f2.8 Fisheye which has a weight of 443g.
Lens Mounts
Both the Sigma 10-18mm F2.8 DC DN C and the Rokinon 8mm f2.8 Fisheye has the same Fujifilm X lens mount. Some of the latest released cameras that are compatible with the Fujifilm X lenses are Fujifilm X-T30 III, Fujifilm X-E5 and Fujifilm X-M5.
Sigma 10-18mm F2.8 DC DN C is also available in the Sony E , Leica L and Canon RF mounts.
Focal Range
Sigma 10-18mm F2.8 DC DN C has a focal range of 10-18mm and
1.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
15-27mm when used on a APS-C / DX format camera.
On the other hand, the Rokinon 8mm f2.8 Fisheye is a prime lens with fixed focal lenght of 8mm which has an effective (full-frame 35mm equivalent) focal range of 12mm when used on a APS-C / DX format camera.