You asked

What are the alternatives to the yongnuo yn42 5mm f 1 7m ii?

Here is what the site says about that.

From Yongnuo YN42.5mm f/1.7M II: Yongnuo YN42.5mm f/1.7M II: A prime lens by Yongnuo for Micro Four Thirds cameras, 42mm f/1.7. A cheap autofocus portrait prime for Micro Four Thirds. Specs - Maker: Yongnuo - Focal length: 42mm (prime) - Maximum aperture: f/1.7 - Made for: Micro Four Thirds sensors - Mounts: Micro Four Thirds - Stabilised: no - Autofocus: yes What it frames like - On Micro Four Thirds (Micro Four Thirds): like 85mm on full frame; f/1.7 ...

From Lenses: Your first lenses: 1. A standard zoom, 24-70mm or 24-105mm equivalent. The kit zoom is fine to start. 2. A fast standard prime, a 50mm f/1.8 on full frame or a 33-35mm f/1.4 to f/1.8 on APS-C. Low light, people, food. 3. Then add for what you shoot: a telephoto zoom for wildlife and sport (wildlife and sport), a wide zoom for landscapes (landscape), or an 85mm for portraits (portraits).

Quoted from this site's pages.

From these pages