You asked
Panasonic leica dg 50 200mm f 2 8 4 vs om system 50 200mm f 2 8?
Both lenses are 50-200mm zooms for Micro Four Thirds, so they frame the same, roughly like a 100-400mm on full frame. They're both stabilised and autofocus. The difference is aperture. The Panasonic Leica DG 50-200mm f/2.8-4 gets darker as you zoom in, while the OM System M.Zuiko 50-200mm f/2.8 IS PRO stays at f/2.8 the whole way and is weather-sealed.
If you shoot wildlife or sport and want a bright lens at full zoom, go with the OM. If you mostly shoot at shorter zooms or in good light, the Panasonic is a sensible alternative. Either way, check the sensor sizes guide if you're unsure how the crop factor affects your framing.
Written by Claude from this site's pages.