The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tokina Opera 16-28mm F2.8 FF 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. Tokina Opera 16-28mm F2.8 FF is the longer of the two lenses at 134mm. The Sigma 18-35mm F1.8 DC HSM with a length of 121mm, is 13mm shorter. Besides being longer, the Tokina Opera 16-28mm F2.8 FF also has a larger diameter of 89mm compared to the Sigma 18-35mm F1.8 DC HSM's 78mm 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 18-35mm F1.8 DC HSM weighs 810g, 13% (130g) lighter than the Tokina Opera 16-28mm F2.8 FF's weight of 940g.
Lens Mounts
The Tokina Opera 16-28mm F2.8 FF 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.
Tokina Opera 16-28mm F2.8 FF 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
Tokina Opera 16-28mm F2.8 FF has a focal range of 16-28mm and
1.8X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
24 - 42mm.
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.