The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang AF 45mm F1.8 FE and the Sigma 4.5mm F2.8 EX DC HSM 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. Sigma 4.5mm F2.8 EX DC HSM Fisheye is the longer of the two lenses at 78mm. The Samyang AF 45mm F1.8 FE with a length of 56mm, is 22mm shorter. Besides being longer, the Sigma 4.5mm F2.8 EX DC HSM Fisheye also has a larger diameter of 76mm compared to the Samyang AF 45mm F1.8 FE's 62mm 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. Samyang AF 45mm F1.8 FE weighs 162g, which means it is 308g (65%) lighter than the Sigma 4.5mm F2.8 EX DC HSM Fisheye which has a weight of 470g.
Lens Mounts
The Samyang AF 45mm F1.8 FE has the Sony E lens mount whereas the Sigma 4.5mm F2.8 EX DC HSM Fisheye has the Canon EF 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 Canon T8i, Canon 90D and Canon SL3 for the Canon EF Mount.
Sigma 4.5mm F2.8 EX DC HSM Fisheye is also available in Sigma SA and Nikon F (DX) mounts.
Focal Range
Samyang AF 45mm F1.8 FE is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
67.5mm.
On the other hand, the Sigma 4.5mm F2.8 EX DC HSM Fisheye is a prime lens with fixed focal lenght of 5mm which has an effective (full-frame 35mm equivalent) focal range of 8mm when used on a APS-C / DX format camera.
