The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 50mm F2.8 Macro and the Sigma 105mm F2.8 EX DG Macro for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Sigma 105mm F2.8 EX DG Macro is the longer of the two lenses at 98mm. The Sony 50mm F2.8 Macro with a length of 60mm, is 38mm shorter. Besides being longer, the Sigma 105mm F2.8 EX DG Macro also has a larger diameter of 74mm compared to the Sony 50mm F2.8 Macro's 72mm diameter.
The weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Sony 50mm F2.8 Macro weighs 295g, which means it is 165g (35%) lighter than the Sigma 105mm F2.8 EX DG Macro which has a weight of 460g.
Below you can find the dimension and weight table of the Macro Prime Lenses in Sony Alpha Mount for size comparison purposes.
Macro Prime Lenses in Sony Alpha Mount for Size Comparison
Lens Mounts
Both the Sony 50mm F2.8 Macro and the Sigma 105mm F2.8 EX DG Macro 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 105mm F2.8 EX DG Macro is also available in Canon EF , Nikon F (FX), Pentax KAF, Sigma SA and Four Thirds mounts.
Focal Range
Sony 50mm F2.8 Macro is a prime lens with fixed focal lenght of 50mm which has an effective (full-frame 35mm equivalent) focal range of 75mm when used on a APS-C / DX format camera. Sigma 105mm F2.8 EX DG Macro is a prime lens with fixed focal lenght of 105mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 157.5mm.