Quite a few 90 postings here, but I'm not sure if anyone has mentioned the three-element f/4 collapsible Elmar? I believe this lens is also called the "mountain" Elmar - presumably because it's light enough for mountaineers to take along. Its claim to fame is that you can stick it in your shirt pocket, and it fits into a standard M3 ER case. But is it really that more compact than, say a f/2.8 Elmarit? How good is it?