A friend of mine wants to get an m43 camera. As it's possible they might never get around to buying another lens I want to advise something around 35-50mm equivalent general purpose prime. They are very keen to try a bit of shallow depth of field subject separation. The price and length of the Oly 45mm 1.8 would be superb for that but I think its too long if they might never get another lens. My question is, is the Oly 25mm 1.8 going to improve the opportunity for shallow dof significantly compared to the cheaper Panny 20mm 1.7? Does that 5mm make much difference for thin depth?