This evening I went through a box that contained all my old Pentax film SLR gear, sorting the wheat from the chaff as I tried to decide what 'stuff' I could use with my new K-30. I had been hoping to use a couple of my M42 lenses on the new camera but after a close inspection it looks like my 28mm prime and my 80-200mm zoom are going to be next to useless!
Both lenses seem to have suffered from an ingress of dust over the years and in one case it looks like a microscopic bug has found it's way onto an inner element. There is no fungus that I can see by looking through either end at a white ceiling and there is no oil on the blades but there are a few visible dust particles which have to be on the inner elements as I scrupulously cleaned the outer glass prior to examining them.
I don't know whether the dust will show in use (the bug probably would) but it looks like they will be staying in the box and most likely will never take a photo again.
At least I have the memories of all the good shots they took when in their prime.
On the plus side my 50mm K-mount prime is still in pristine condition so that should get some use again.