It sounds like the hood for the ST 35/3.5. Sometimes they are a little tight to rotate. As long as you can get the hood to properly line up (do you know the technique for that?), you'll be fine.
There was, I believe, a similar hood for the 50mm lens, although I've never seen one. The hood should be marked as to the lens it's for. Shel > [Original Message] > From: cbwaters > Hey, I've just bought a rectangular Takumar lens hood. > It's a 49mm. Screwed onto the M 40mm pancake lens > I had with me, it gets tight at something other than 90* > to the camera body. Is there anything to be done > about it? Is it important? What's this hood meant for? -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net

