FYI, It is listed on the Canon Camera Museum site: http://www.canon.com/camera-museum/c...5/s_35_15.html

The 35/1.5 is probably a double Gauss derivative, as this seems to have been the basis for most Canon LTM lenses. FWIW, the 35/1.8 is 7 elements in 4 groups and is definitely a double Gauss type; I can't find a block diagram for the 35/1.5, but it is listed as 8 elements in 4 groups.

Out of my price range, but GLWS.