You asked
Best portrait lens for the om system pen?
For portraits on the OM System PEN, I'd start with an 85mm-equivalent prime. The Olympus M.Zuiko 45mm f/1.2 PRO frames like 90mm on full frame and gives you a lovely background blur at f/1.2. If you want something a little more compact, the Panasonic Leica DG 42.5mm f/1.2 works in the same range, framing like 85mm.
If you want to spend less, the Olympus M.Zuiko 45mm f/1.8 is a sensible everyday choice.
Whichever you pick, remember that portraits are mostly about light. Put your subject near a window and expose for the face, and you'll get more out of any lens. For the wider picture on building a kit, see your first lenses.
Written by Claude from this site's pages.