The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Nikon AF-P DX 10-20mm F4.5-5.6G VR 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 Nikon AF-P DX 10-20mm F4.5-5.6G VR with a length of 73mm, is 5mm shorter. On the other hand, the Nikon AF-P DX 10-20mm F4.5-5.6G VR has a larger diameter of 77mm 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. Nikon AF-P DX 10-20mm F4.5-5.6G VR weighs 230g, which means it is 240g (51%) lighter than the Sigma 4.5mm F2.8 EX DC HSM Fisheye which has a weight of 470g.
Lens Mounts
Both the Nikon AF-P DX 10-20mm F4.5-5.6G VR and the Sigma 4.5mm F2.8 EX DC HSM Fisheye has the same Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with the Nikon F (DX) lenses are Nikon D3500, Nikon D7500 and Nikon D5600.
Sigma 4.5mm F2.8 EX DC HSM Fisheye is also available in Canon EF and Sigma SA mounts.
Focal Range
Nikon AF-P DX 10-20mm F4.5-5.6G VR has a focal range of 10-20mm and
2.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
15-30mm when used on a APS-C / DX format camera.
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.