Okay so maybe this is a dumb question. I was recently given the Nikon D200 for christmas and recently bought 2 lenses. Each lens has a rotating ring nearest/closest to the body where it attaches to the camera. What is that rotating ring for? When I am zooming or focusing and I accidently rotate that ring, my camera no longer lets me push the shutter button to take a photo. Is this ring for anything particular or is it just a rotating ring for looks? Again, I apologize if this is a really out there dumb question but I have always been told a dumb question is one not asked. i have a sigma 70-210 and a nikkor 28-100 and i am shooting manual in both here is a photo of my 70-210 and the part with the aperture numbers on it....where there is out a auto/manual lock function that ring is the one that turns.