Ok, let's refocus this discussion ... 1) The lens is a near-
symmetrical double Gauss lens with eight elements in six groups.
2) The external menisci were set with the concave side pointing
outward, but that may have been the result of storage (to avoid
protruding lens surfaces being scratched accidentally) 3) The
lens mount has large perforations either for cooling or heating
of the lens assembly 4) The lens mount as found is in itself
complete and has no (space for a) diaphragm. 5) The centre of
the lens mount (on the smaller side) has an external thread,
which suggests that a cover/cone could have been screwed on
here. A narrow groove would provide a light tight end to this
This may suggest that the part that protruded from the unit was
the section with the smaller diameter, rather than the section
with the wider one. That interpretation is supported by the
orientation of the fasting screws on the lens mount. 6) There
are no markings except for numbers on the metal fittings. The
lens glass is unnumbered 7)