The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 20-40mm F2.8 VXD and the Sony FE 28-70mm F3.5-5.6 OSS 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. Tamron 20-40mm F2.8 VXD is the longer of the two lenses at 86mm. The Sony FE 28-70mm F3.5-5.6 OSS with a length of 83mm, is 3mm shorter. Besides being longer, the Tamron 20-40mm F2.8 VXD also has a larger diameter of 74mm compared to the Sony FE 28-70mm F3.5-5.6 OSS's 73mm diameter.
Below you can find a scaled side-by-side image of Tamron 20-40mm F2.8 VXD and Sony FE 28-70mm F3.5-5.6 OSS to get a better idea of how their sizes compare in real life.
Comparison image of the Tamron 20-40mm F2.8 VXD and the Sony FE 28-70mm F3.5-5.6 OSS Size and Weight 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 FE 28-70mm F3.5-5.6 OSS weighs 295g, 19% (70g) lighter than the Tamron 20-40mm F2.8 VXD's weight of 365g.
Lens Mounts
Both the Tamron 20-40mm F2.8 VXD and the Sony FE 28-70mm F3.5-5.6 OSS has the same Sony E lens mount. Some of the latest released cameras that are compatible with the Sony E lenses are Sony ZV-E1, Sony A7R V and Sony FX30.
Focal Range
Tamron 20-40mm F2.8 VXD has a focal range of 20-40mm 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 30 - 60mm.
Sony FE 28-70mm F3.5-5.6 OSS has a focal range of 28-70mm and 2.5X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 42 - 105mm.