The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 15-30mm f2.8 VC USD and the Sigma 20mm F1.8 EX DG RF 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. Tamron 15-30mm f2.8 VC USD is the longer of the two lenses at 145mm. The Sigma 20mm F1.8 EX DG RF with a length of 90mm, is 55mm shorter. Besides being longer, the Tamron 15-30mm f2.8 VC USD also has a larger diameter of 98mm compared to the Sigma 20mm F1.8 EX DG RF's 89mm 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 20mm F1.8 EX DG RF weighs 520g, 52% (580g) lighter than the Tamron 15-30mm f2.8 VC USD's weight of 1100g.
Lens Mounts
Both the Tamron 15-30mm f2.8 VC USD and the Sigma 20mm F1.8 EX DG RF 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 15-30mm f2.8 VC USD is also available in the Canon EF and Nikon F (FX) mounts.
Sigma 20mm F1.8 EX DG RF is also available in Canon EF , Nikon F (DX), Pentax KAF and Sigma SA mounts.
Focal Range
Tamron 15-30mm f2.8 VC USD has a focal range of 15-30mm and
2.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
22.5 - 45mm.
On the other hand, the Sigma 20mm F1.8 EX DG RF is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 30mm.
