I don't forem much, new so I will try to get this fix posted and reply'd to same question-problem...hence...Sigma 28mm Mini-Wide macro lens will NOT mount on my K-50 or other K newer camera's...answer & fix: I took a razor knife and prune down, the errant guard. This is easy to do - it's only plastic. So now it mounts perfectly. But as I posted earlier, the lens looks like it was sprayed with hairspray or krylon paint on the inside. Doesn't look like a fungus. Like a film and everything viewed is in a mist-fog. What is that??? I emailed the ebay seller, he gladly refunded me but now I got like two weeks behind. Had he just knew anything about lenses he would have seen thi. Yet his listing stated Mint, clear lens, excellent.