I ordered a 3.8 lens from aliexpress for about 60$ : 1/2.3" 3.8MM Lens 16Megapixel M12 Mount Low Distortion for Gopro 4 Black Camera 2016 Newly Coming-in CCTV Lenses from Security & Protection on Aliexpress.com | Alibaba Group
Very happy of the result :
Rainy day in the air :
Hand held :