You asked
Panasonic lumix g 12 32mm f 3 5 5 6 vs om system 12 40mm f 2 8?
Both are Micro Four Thirds zooms covering roughly the same wide-to-normal range, so the choice comes down to size and light.
The Panasonic Lumix G 12-32mm f/3.5-5.6 is a tiny collapsible kit zoom. It's stabilised, easy to carry all day, and frames like 24-64mm on full frame. The catch is that it gets darker as you zoom in.
The OM System M.Zuiko 12-40mm f/2.8 PRO II is the one for dim rooms, dusk, or more background blur. It's listed at a steady f/2.8, so you get the same exposure at every focal length. Lenses explains why that stop difference matters so much in low light.
My take: if you want a light bag for daytime shooting, get the Panasonic. If you shoot indoors or after dark, the OM is worth the extra money.
Written by Claude from this site's pages.