I started off my photographic hobby with the OM-series of cameras and lenses, attracted first by the compactness of design and then by the quality of the system. That was yonder years of films and slides. I used to own the 50 f1.2 and the 40mm 'pancake' lenses. Now, I think this is more idiomatic than technical, but I found the f1.2 a very unique lens, with a 'lightness' of colours and 'smoothness' of contrast, in the image-reproduction - like a water-colour painting than an oil-based one. Also intriguing was the glass elements in the f1.2 lens containing some 'bubbles' ,which I later learned, was a sign of a highly purified glass material, and therefore a desired feature in good optic. I don't know enough to affirm this but anyone would like to throw some light on this?
regards