The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 85mm F1.8 VC and the Sigma 70-300mm F4-5.6 DG 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 70-300mm F4-5.6 DG is the longer of the two lenses at 122mm. The Tamron 85mm F1.8 VC with a length of 91mm, is 31mm shorter. On the other hand, the Tamron 85mm F1.8 VC has a larger diameter of 85mm compared to the Sigma 70-300mm F4-5.6 DG's 77mm 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 70-300mm F4-5.6 DG weighs 550g, 21% (150g) lighter than the Tamron 85mm F1.8 VC's weight of 700g.
Filter Threads
The Tamron 85mm F1.8 VC has a filter size of 67mm whereas the Sigma 70-300mm F4-5.6 DG has a 58mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Tamron 85mm F1.8 VC:
And these are the 58mm filters that we recommend for the Sigma 70-300mm F4-5.6 DG:
Lens Mounts
Both the Tamron 85mm F1.8 VC and the Sigma 70-300mm F4-5.6 DG has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Tamron 85mm F1.8 VC is also available in the Canon EF and Nikon F (FX) mounts.
Sigma 70-300mm F4-5.6 DG is also available in Canon EF , Nikon F (FX), Pentax KAF, Sony Alpha, Sigma SA, Canon EF, Nikon F (FX), Pentax KAF and Sigma SA mounts.
Focal Range
Tamron 85mm F1.8 VC is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
127.5mm.
On the other hand, the Sigma 70-300mm F4-5.6 DG has a focal range of 70-300mm and 4.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 105 - 450mm.
