The positives: Quality construction and very high sharpness from f/2! Especially from f/2.5 and above, nothing changes, the sharpness remains excellent throughout the image. On Nikon cameras, you adjust the aperture from the camera button, not manually. Only the focus is manual, which is done accurately only through live view on the D3xxx and D5xxx series. It is one of the fastest lenses at 16mm. The second lens that achieves this is the Tokina 14-20mm, but it costs 900 euros! It is ideal for astrophotography and landscape photography.

The negatives: It weighs about half a kilo (but still compared to the equivalent for full frame, it's fine) and the focus is manual, which will slow you down if you need to focus frequently due to changing the focal distance. Especially for the 3xxx and 5xxx series.

Things change with the 7000, 7100, 7200, and 7500 because they have a mechanism that informs you with visual and auditory signals when it is focused on the subject it sees! I should clarify that in the 7500, which I own, there is a visual signal through the viewfinder, but there is no mechanism for automatic metering (ai indexing tab) for manual lenses, which hasn't caused me any difficulties since this lens has a communication chip with the camera. In Aperture mode, I adjust the aperture from the camera dial and the ISO manually or automatically like with all lenses. Then the camera adjusts the shutter speed on its own (and the ISO when it's in automatic mode).

I would also like to add that it produces no flares unlike the Tokina 11-16 DXII, which I compared side by side and the results from the latter were terrible. Even the Nikon 16-80, which is considered one of Nikon's best for DX cameras, produces some flares, albeit reduced compared to the Tokina. However, the Samyang in the same scenario didn't produce the slightest flare. Very impressive result.

Finally, the Samyang 16mm F/2.0 produces very impressive stars from f/9 and above, with 8 rays. In contrast to the Tokina and Nikon.

I use it with a D5500 for landscapes and astrophotography and I am very satisfied!

(Update) Now I use it with a D7500 and I can say that it works flawlessly and without tiring.

Excellent lens... Incredibly sharp!
The focus ring is very smooth and has a wide range, which makes it very easy to use!
Sturdy and made with high-quality plastics, it never gives you the feeling of being "cheap".

Another excellent lens from Samyang!
P.S. I use it on a Canon 700D