Abstract
The lens I was using has oily blades. This means that the aperture that normally closes during an exposure cannot move fast enough, or at all, while the shutter is firing. The result is out-of-focus mush. While it pisses me off extremely that this is my favorite lens and it has a problem that needs fixed, these lens errors can sometimes product unexpected interesting results that are worth keeping. I thought this was one of them.
Ironically, the lens was one of my newest, a 200mm Macro lens made in the middle 1980s and 90s.
Pentax K-1 mII, A*200f2.8 ED Macro