The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Samyang 20mm F1.8 and the Tamron 17-35mm f2.8-4 LD 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. Samyang 20mm F1.8 is the longer of the two lenses at 88mm. The Tamron 17-35mm f2.8-4 LD with a length of 87mm, is 1mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 83mm.
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 LD weighs 440g, 11% (57g) lighter than the Samyang 20mm F1.8's weight of 497g.
Filter Threads
Both the Samyang 20mm F1.8 and the Tamron 17-35mm f2.8-4 LD have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Samyang 20mm F1.8 and the Tamron 17-35mm f2.8-4 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.
Samyang 20mm F1.8 is also available in Canon EF-M , Fujifilm X, Micro Four Thirds, Nikon F (FX), Pentax KAF, Samsung NX, Sony Alpha and Sony E mounts.
Tamron 17-35mm f2.8-4 LD is also available in Nikon F (FX) mount.
Focal Range
Samyang 20mm F1.8 is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
On the other hand, the Tamron 17-35mm f2.8-4 LD has a focal range of 17-35mm and 2.1X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 27.2 - 56mm.