135mm DC noise when shake
Hi everyone. I've just bought an used 135mm f/2 DC lens. When I shake the lens, I hear some strange sound, like the front optic element was loosen. Put the lens up side down and use my finger to carefully push the front element, I can feel it move! Is this normal with this lens? I thought the front optic element should be sealed to prevent dust enter the lens. Should I send it to Nikon services for repairing? Please help!
sorry for my bad English.