I'm looking for a lens hood for the Pentax 55mm/f1.8 that I just picked up. Barring an OE hood (which I gather is even more scarce than the lens [and ridiculously ex$pensive]), I picked up an Altura tulip style hood. Not period correct, but I really didn't care. But the d#@* thing won't thread on. Not onto the filter nor onto the lens itself, so back it goes. Barring paying retail at the closest shop, can somebody recommend a source for either a thread-on hood or one that has a threaded adapter onto which the hood can bayonet (similar to modern lenses)? Many thanks!