Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Samyang AF 18mm F2.8 FE is the longer of the two lenses at 61mm. The Sigma 17mm F4 DG DN C with a length of 49mm, is 12mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 64mm.
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. Samyang AF 18mm F2.8 FE weighs 145g, 35% (80g) lighter than the Sigma 17mm F4 DG DN C's weight of 225g.
Filter Threads
The Sigma 17mm F4 DG DN C has a filter size of 55mm whereas the Samyang AF 18mm F2.8 FE 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 55mm filters that we recommend you to consider for the Sigma 17mm F4 DG DN C:
And these are the 58mm filters that we recommend for the Samyang AF 18mm F2.8 FE:
Lens Mounts
The Sigma 17mm F4 DG DN C has the Leica L lens mount whereas the Samyang AF 18mm F2.8 FE has the Sony E lens mount. Some of the latest released cameras that are compatible with these mounts are Leica SL3-P, Panasonic S1 II and Panasonic S1 IIE for the Leica L Mount and Sony FX5, Sony A7R VI and Sony A7 V for the Sony E Mount.
Sigma 17mm F4 DG DN C is also available in the Sony E mount.
Focal Range
Sigma 17mm F4 DG DN C is a prime lens with fixed focal lenght of 17mm.
On the other hand, the Samyang AF 18mm F2.8 FE is a prime lens with fixed focal lenght of 18mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of 27mm.
