Review: Solinon M 18mm 5.6 Asph :
https://phillipreeve.net/blog/review-so ... -5-6-asph/
Alternatives : Laowa 15mm 5.0 “Cookie”:
This Solinon has a more even across frame performance at infinity,
better flare resistance and less distortion as well as CA.
The Laowa is even smaller, slightly cheaper and focuses closer.
Pick depending on your needs and focal length preferences!