The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony FE 28-70mm F3.5-5.6 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. Sony FE 28-70mm F3.5-5.6 is the longer of the two lenses at 83mm. The Rokinon 7.5mm f3.5 Fisheye with a length of 48mm, is 35mm shorter. Besides being longer, the Sony FE 28-70mm F3.5-5.6 also has a larger diameter of 73mm compared to the Rokinon 7.5mm f3.5 Fisheye's 60mm 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. Rokinon 7.5mm f3.5 Fisheye weighs 197g, 33% (98g) lighter than the Sony FE 28-70mm F3.5-5.6's weight of 295g.
Lens Mounts
The Sony FE 28-70mm F3.5-5.6 has the Sony E lens mount whereas the Rokinon 7.5mm f3.5 Fisheye has the Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with these mounts are Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount and OM System OM-3 Astro, OM System OM-5 II and OM System OM-3 for the Micro Four Thirds Mount.
Focal Range
Sony FE 28-70mm F3.5-5.6 has a focal range of 28-70mm and
2.5X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
42 - 105mm.
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.
