Hello everyone, I recently purchased a Zeiss Ikon contaflex with a Tessar 2.8 Carl Zeiss lens on a compu-Shutter. I love the little camera and the image quality is not bad. The lens has a rim of "crap" on its outer edge. The center of the lens is clear. I am trying to find out if this lens can be cleaned from the back somehow without a very involved proccess. I don't see how to take it off. I am attaching a picture of the lens. Thanks in advance.