The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 45mm F1.8 Di VC USD and the Sigma 50mm F2.8 EX DG Macro for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Tamron 45mm F1.8 Di VC USD is the longer of the two lenses at 92mm. The Sigma 50mm F2.8 EX DG Macro with a length of 67mm is 25mm shorter. Besides being longer, the Tamron 45mm F1.8 Di VC USD also has a larger diameter of 80mm compared to Sigma 50mm F2.8 EX DG Macro's 71mm diameter.
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. Sigma 50mm F2.8 EX DG Macro weighs 320g, 38% (200g) lighter than the Tamron 45mm F1.8 Di VC USD's weight of 520g.
Lens Mounts
Both Tamron 45mm F1.8 Di VC USD and Sigma 50mm 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 A99 II, Sony A68 and Sony A77 II.
Tamron 45mm F1.8 Di VC USD is also available in Canon EF and Nikon F (FX) mounts.
Sigma 50mm F2.8 EX DG Macro is also available in Canon EF , Pentax KAF, Sigma SA and Nikon F (FX) mounts.
Focal Range
Tamron 45mm F1.8 Di VC USD is a prime lens with fixed focal lenght of 45mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 67.5mm.
Sigma 50mm F2.8 EX DG Macro is a prime lens with fixed focal lenght of 50mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 75mm.