I committed myself to use the Industar-61 L/Z 50mm F2.8 for the whole month of April at least for one photo a day. It's the so-called 'Single in...." challenge at Pentaxforums.com, with a dedicated group at flickr too. Well, I love this lens. It's an oldie from the Former Soviet Union, with a close focus capability and a weird star-shaped aperture. Seek the internet, and you will find lots of info.
One of the things I discovered the first part of this month is, that the lens is quite capable of taking very decent flower close-ups at or nearby open aperture. The bokeh is most of the time very soft and creamy, but when the background is near, it's swirly, or painterly. An example is this shot of Muscari I made today. If you can lay your hands on this lens you should consider it seriously!