The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-35mm F1.8 DC HSM and the Tamron 15-30mm f2.8 VC USD 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 18-35mm F1.8 DC HSM with a length of 121mm, is 24mm shorter. Besides being longer, the Tamron 15-30mm f2.8 VC USD also has a larger diameter of 98mm compared to the Sigma 18-35mm F1.8 DC HSM's 78mm diameter.
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Below you can find a scaled side-by-side image of Sigma 18-35mm F1.8 DC HSM and Tamron 15-30mm f2.8 VC USD to get a better idea of how their sizes compare in real life.
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 18-35mm F1.8 DC HSM weighs 810g, which means it is 290g (26%) lighter than the Tamron 15-30mm f2.8 VC USD which has a weight of 1100g.
Lens Mounts
The Sigma 18-35mm F1.8 DC HSM has the Nikon F (DX) lens mount whereas the Tamron 15-30mm f2.8 VC USD has the Nikon F (FX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount and Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount.
Sigma 18-35mm F1.8 DC HSM is also available in Canon EF , Pentax KAF, Sony Alpha and Sigma SA mounts.
Tamron 15-30mm f2.8 VC USD is also available in Canon EF and Sony Alpha mounts.
Focal Range
Sigma 18-35mm F1.8 DC HSM has a focal range of 18-35mm and
1.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-52.5mm when used on a APS-C / DX format camera.
On the other hand, the 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.