Quote Originally Posted by Bob-D659 View Post
You can measure the distance from that mark to the front of the lens mount yourself, and from a quick google, it should be around 101mm. Info from here

http://www.graphics.cornell.edu/~wes...habetical.html
101 mm is the distance for Bronica s2a not SQ.
My friend found another site: http://www.geocities.co.jp/Hollywood/1089/mounts.html