The 50mm 1.8 is a good buy as others have said. The general internet reviews point to the black barrel version being the sharpest but I think the chrome serenar does just as well and looks great with bw film. If you want a summitar look the 50mm 1.9 is a very close version to it. Collapsible as well but it won't fit into your P all the way. Also unlike the summitar the coating is harder and you can find versions with the front elements in much better condition. I like both, the 1.8 is sharper wide open and more contrasty the 1.9 is softer with lower contrast and smooth tones.