Vivitar 28mm 2.8 question
I found this lens in my parents house. Vivitar 28mm 2.8. There were also 2 adapters that fit on the back of the lens and securely attach to the back of the lens. Can someone tell me what those adapters are called? I know they fit a M42 mount.
Flickr Photo stream: http://www.flickr.com/photos/jacobcaddy/