The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 15mm F2.8 EX DG Fisheye 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 Sigma 15mm F2.8 EX DG Fisheye with a length of 65mm, is 13mm shorter. Besides being longer, the Sigma 4.5mm F2.8 EX DC HSM Fisheye also has a larger diameter of 76mm compared to the Sigma 15mm F2.8 EX DG Fisheye's 74mm 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 15mm F2.8 EX DG Fisheye weighs 370g, which means it is 100g (21%) lighter than the Sigma 4.5mm F2.8 EX DC HSM Fisheye which has a weight of 470g.
Below you can find the dimension and weight table of the Wideangle Fisheye Prime Lenses in Sigma SA Mount for size comparison purposes.
Ultra-Wideangle Lenses in Sigma SA Mount for Size Comparison
Lens Mounts
Both the Sigma 15mm F2.8 EX DG Fisheye and the Sigma 4.5mm F2.8 EX DC HSM Fisheye has the same Sigma SA lens mount. Some of the latest released cameras that are compatible with the Sigma SA lenses are Sigma Quattro, Sigma Quattro H and Sigma SD1 Merrill.
Sigma 15mm F2.8 EX DG Fisheye is also available in the Canon EF , Nikon F (FX), Pentax KAF and Sony Alpha mounts.
Sigma 4.5mm F2.8 EX DC HSM Fisheye is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Sigma 15mm F2.8 EX DG Fisheye is a prime lens with fixed focal lenght of 15mm.
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.
