The lens board has a metal stamped impression in it that is the name
of the craftsman that did the conversion or the name of the company
he worked for. It is a form of logo name stamp that obviously was
custom made for "E. Schlegel N.Y.C.". They must have been
camera technicians that wanted to mark their work. The aperture is
wider than today's Super 35. The image field actually goes into the
sprocket holes.