The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 24-70mm f2.8 VC USD and the Tamron AF 28-75mm f2.8 XR LD 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 24-70mm f2.8 VC USD is the longer of the two lenses at 117mm. The Tamron AF 28-75mm f2.8 XR LD with a length of 92mm is 25mm shorter. Besides being longer, the Tamron 24-70mm f2.8 VC USD also has a larger diameter of 88mm compared to Tamron AF 28-75mm f2.8 XR LD's 73mm 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. Tamron AF 28-75mm f2.8 XR LD weighs 510g, 38% (315g) lighter than the Tamron 24-70mm f2.8 VC USD's weight of 825g.
Below you can find the dimension and weight table of the 'Standard Zoom Lenses in Canon EF Mount for size comparison purposes.
Standard Zoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both Tamron 24-70mm f2.8 VC USD and Tamron AF 28-75mm f2.8 XR LD has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Tamron 24-70mm f2.8 VC USD is also available in Nikon F (FX) and Sony Alpha mounts.
Tamron AF 28-75mm f2.8 XR LD is also available in Nikon F (FX) , Sony Alpha and Pentax KAF mounts.
Focal Range
Tamron 24-70mm f2.8 VC USD has a focal range of 24-70mm and 2.9X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 38.4 - 112mm.
Tamron AF 28-75mm f2.8 XR LD has a focal range of 28-75mm and 2.7X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides an 35mm (FF) equivalent of 44.8 - 120mm.