You asked
What lenses should I buy for the om system pen?
For an everyday kit on the OM System PEN, I'd start with the Panasonic Leica DG 12-35mm f/2.8. It frames like a 24-70mm on full frame, so it covers most street, travel and family shots, and the f/2.8 aperture is useful in lower light.
For a lighter setup, add the Panasonic Lumix G 25mm f/1.7. It frames like a 50mm and suits the PEN's rangefinder style well.
For portraits, the Olympus M.Zuiko 45mm f/1.8 gives a flattering, tighter view, like 90mm on full frame.
You can see every lens that fits the PEN on its camera page.
Written by Claude from this site's pages.