I posted this on another forum, but never thought to ask the helpful people here -- before now! A while back I bought a cheap eBay adapter which only locks into place on certain of my K-mount lenses. In particular my FA Limiteds do not lock, and so can easily be rotated off the adapter. Certainly not something I want to have happen! Can someone point me to a cheap adapter that dependably works? I know there are some, but no-one has so far come up with a name or link.