The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony DT 11-18mm F4.5-5.6 and the Sigma 15mm F2.8 EX DG 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. Sony DT 11-18mm F4.5-5.6 is the longer of the two lenses at 81mm. The Sigma 15mm F2.8 EX DG Fisheye with a length of 65mm, is 16mm shorter. Besides being longer, the Sony DT 11-18mm F4.5-5.6 also has a larger diameter of 83mm 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. Sony DT 11-18mm F4.5-5.6 weighs 360g, which means it is 10g (2%) lighter than the Sigma 15mm F2.8 EX DG Fisheye which has a weight of 370g.
Lens Mounts
Both the Sony DT 11-18mm F4.5-5.6 and the Sigma 15mm F2.8 EX DG Fisheye has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.
Sigma 15mm F2.8 EX DG Fisheye is also available in Canon EF , Nikon F (FX), Pentax KAF and Sigma SA mounts.
Focal Range
Sony DT 11-18mm F4.5-5.6 has a focal range of 11-18mm and
1.6X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
16.5-27mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 15mm F2.8 EX DG Fisheye is a prime lens with fixed focal lenght of 15mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 22.5mm.
