No name on shutter, just lens cells.

I removed the remainder of the linkages inside and left external
things on for cosmetic appeal (air cylinders & a nickel plated plate
with arrow that I can't get of anyway).

I had a 2-45 mm opening iris from surplus shed (origin either Edmund
or Melles Griot). Made a sketch for 'truncated annular ring' spacer,
a ring the same thickness as the iris body, i.d. just larger than the
iris body and o.d. just smaller than the shutter body i.d. The iris
has a lever that moves 90 degrees. The ring will be 'truncated' by
cutting a segment about 120 degrees out of the perimeter to pass the
lever. It will be mounted upside down (from the iris scale) in the
shutter body because there is already some slotting from non-existent
levers which if extended a little further will allow passage of the
iris lever.

Iris has no stops and moves too easily. The moving part is accessible
and slightly recessed. I may shim that with some fluoropolymer tape
(self adhesive) to give some friction.

2 holes thru the spacer adapter to clear the 2 screws that hold the
two shutter body shells together will finish it.

I am debating glue or three set screws in the ring's perimeter. The
blades are offset from center so reversing the iris body in the
adapter would allow placing the 'stop' in whichever position relative
to either element is more 'correct'. I'm not sure how to determine
that anyway. I imagine centered would be for 1:1, and some offset away
for infinity, NO idea whether it should be fore or aft, so it may be
that 'closest to center' may be the 'least wrong' rather than best
position.

It is so simple it could be made on a wood lathe. I was going to try a
fly cutter hole saw in plywood, but that would defy Murray's Law. Or
define, I'm not sure...

If only a shutter were as easy and fit inside (not much room left).

Murray