Hey All, Stumbled across a Vivitar 28mm 2.5 in m42 mount at an estate sale for $10. Even though I have and love the Close focus f2 I have, I decided to pick it up as it was "different" by having a stop-down ring along with the aperture. Listed as M15 on the Great Vivitar Bestiary. The only "issue" may be that the secondary ring (the one right below the aperture ring) is VERY easy to turn, and doesn't have any kind of click/detent at each end to keep it there. Is this normal for others who may have this kind-of unique lens or do I need to tear it down and replace something (perhaps someone de-clicked it)? From just holding the lens, I can even "bounce" the ring back off the hard stop at either end, so it will be a "make sure it is open" kind of thing. However, focusing should be easier since I can set the aperture, open it up, focus and then stop down without counting... I have also heard that the bottom-most ring is a T-m42 adapter that was put on the lens initially. Can anyone confirm/deny? Also, anyone have any experience with a m42 to MD adapter? Instead of picking up another whole adapter, just stacking would be cheaper (and could really be cheaper if I invest in a second mirrorless system).