It is positively tiny with very odd hood. For now I decided to put the hood aside. I have an alternative solution thanks to the common for Pentax filter thread - 49 mm. Few test shots showed that this lens is very sharp. Also the quick shift focus meachanism is a charm. I wonder what kept Pentax from introducing it a long long long time ago.
Here is one of the shots that although does not fit as a test shot but still is quite pleasing. I used a polar filter this time.