The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 17-35mm F2.8-4 Di OSD and the Sigma 18-35mm F1.8 DC HSM 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. Sigma 18-35mm F1.8 DC HSM is the longer of the two lenses at 121mm. The Tamron 17-35mm F2.8-4 Di OSD with a length of 93mm, is 28mm shorter. On the other hand, the Tamron 17-35mm F2.8-4 Di OSD has a larger diameter of 84mm 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 Tamron 17-35mm F2.8-4 Di OSD and Sigma 18-35mm F1.8 DC HSM 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. Tamron 17-35mm F2.8-4 Di OSD weighs 460g, which means it is 350g (43%) lighter than the Sigma 18-35mm F1.8 DC HSM which has a weight of 810g.
Filter Threads
The Tamron 17-35mm F2.8-4 Di OSD has a filter size of 77mm whereas the Sigma 18-35mm F1.8 DC HSM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 77mm filters that we recommend you to consider for the Tamron 17-35mm F2.8-4 Di OSD:
And these are the 72mm filters that we recommend for the Sigma 18-35mm F1.8 DC HSM:
Lens Mounts
The Tamron 17-35mm F2.8-4 Di OSD has the Nikon F (FX) lens mount whereas the Sigma 18-35mm F1.8 DC HSM has the Nikon F (DX) lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and Nikon D3500, Nikon D7500 and Nikon D5600 for the Nikon F (DX) Mount.
Tamron 17-35mm F2.8-4 Di OSD is also available in Canon EF mount.
Sigma 18-35mm F1.8 DC HSM is also available in Canon EF , Pentax KAF, Sony Alpha and Sigma SA mounts.
Focal Range
Tamron 17-35mm F2.8-4 Di OSD has a focal range of 17-35mm and
2.1X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
25.5 - 52.5mm.
On the other hand, the 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.