The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 24-70mm F2.8 II 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 24-70mm F2.8 II is the longer of the two lenses at 122mm. The Sigma 4.5mm F2.8 EX DC HSM Fisheye with a length of 78mm, is 44mm shorter. Besides being longer, the Sigma 24-70mm F2.8 II also has a larger diameter of 88mm compared to the Sigma 4.5mm F2.8 EX DC HSM Fisheye's 76mm 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 4.5mm F2.8 EX DC HSM Fisheye weighs 470g, 36% (265g) lighter than the Sigma 24-70mm F2.8 II's weight of 735g.
Lens Mounts
The Sigma 24-70mm F2.8 II has the Sony E lens mount whereas the Sigma 4.5mm F2.8 EX DC HSM Fisheye has the Sigma SA 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 Sigma SD1 Merrill, Sigma SD1 and for the Sigma SA Mount.
Sigma 24-70mm F2.8 II is also available in the Leica L mount.
Sigma 4.5mm F2.8 EX DC HSM Fisheye is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Sigma 24-70mm F2.8 II has a focal range of 24-70mm and
2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
36 - 105mm.
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 7.5mm when used on a APS-C / DX format camera.
