The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 10-20mm F3.5 EX DC HSM 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 10-20mm F3.5 EX DC HSM is the longer of the two lenses at 88mm. The Sigma 4.5mm F2.8 EX DC HSM Fisheye with a length of 78mm, is 10mm shorter. Besides being longer, the Sigma 10-20mm F3.5 EX DC HSM also has a larger diameter of 87mm 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, 9% (50g) lighter than the Sigma 10-20mm F3.5 EX DC HSM's weight of 520g.
Lens Mounts
Both the Sigma 10-20mm F3.5 EX DC HSM 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 SD1 Merrill, Sigma SD1 and .
Sigma 10-20mm F3.5 EX DC HSM is also available in the Canon EF , Pentax KAF3, Sony Alpha and Nikon F (DX) mounts.
Sigma 4.5mm F2.8 EX DC HSM Fisheye is also available in Canon EF and Nikon F (DX) mounts.
Focal Range
Sigma 10-20mm F3.5 EX DC HSM 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.
