The lens is a Samyang 500mm f/6.3 mirror prime:
It doesn't have autofocus, zoom or diaphragm. It is a pretty frugal design, just like a catadioptric telescope with a camera mount instead of an eyepiece. It is hard to focus given its small depth of field for the focal distance and the travel range of the focus ring. Many people don't like it's donut shaped bokeh. But still I found it a very interesting lens for its focal length, size and reasonable speed. It basically can do what no other 150 Euro lens can do. And sometimes getting a great shot is not about the bokeh, the sharpness, contrast, etc, but about simply getting the shot, capturing the moment, telling the story.
While not having had much time to perfection the shooting, I have made a few shots taking advantage of the view around my balcony, which covers a little bit of Almada, the Tagus river and Lisbon.
Train station, at about 600 meters of distance:
Old Almada, about 3 Km away:
Panteão Nacional (mausoleum), about 7 km away:
Soccer field lamp, 500 meters away:
Church inside Lisbon, about 7 km far:
In the field of astrophotography the lens capabilities are yet to be tested. The area where I live is complicated because of the heavy light polution of the cities nearby.