What might cause stuck focus on a manual lens?

Question

So, today I dropped my ME Super. When I picked it up I realized that the focus ring of the 50mm f2 lens attached didnt turn. My question is, what could cause this? Could it be that the threads inside the lens which move the glass about are binding?

Answer

My problem was that the threads that move the elements were jammed. I was lucky as in this lens, a Pentax SMC-M 50mm f2, all of the glass was contained in a unit and a thread moved it back and forth or obtain focus. These threads had slipped and basically they were cross threaded. I would never try this on an autofocus lens or a zoom lens. That would be WAY to complicated. Even with a prime lens it took a lot of adjustment to get the distance scale correct and I couldn't even begin to imagine what a nightmare it would be on a zoom lens. Sorry jrista, a step by step would look like this: Disassemble Repair Reassemble Check focus Disassemble Adjust Reassemble And repeat......

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