The 50mm focal length is the lens of choice for a lot of photographers. It is commonly used for portraits and street photography. Even though I’ve used it for both applications, I find that it excels in landscape and architecture.
The 50mm Loxia is special since it's sharp even at f2. It's small and matches with the other Zeiss Loxia.
Taking the 50mm along with the 21mm will give you enough to work with as far as focal length and coverage. Yet, If I had to take one lens to the city it would be 50mm. A 50mm gives you the ability to tell a different story in cities like New York, Chicago, or Boston where it's easy to throw on a wide‑angle lens and try to get as much in the frame as possible.
Another approach I take with the 50mm Loxia is using it with crop mode in the Sony A7RIII. If I need extra reach, I can crop in 1.5x essentially giving me a 75mm focal length. Because of the high resolution of both the A7RIII and Loxia lines up, I still have images that produce plenty of detail, like the image above.
The Zeiss Loxia 50mm f2 also excels as a portrait lens