You asked
Best budget lens for the panasonic lumix gx850?
For the GX850, I'd start with the Panasonic Lumix G 14-42mm f/3.5-5.6 II. It's a simple everyday zoom that frames like 28-84mm on full frame, and it suits the GX850's small, light body.
If you want something fast and cheap, get the Panasonic Lumix G 25mm f/1.7. It frames like a 50mm and is good for portraits and low light.
For wide scenes, the Panasonic Lumix G 14mm f/2.5 II is a small, sensible pick.
Spending a bit more on a good lens than on the body is a sound rule. See your first camera.
Written by Claude from this site's pages.