Stereo 225 (aperture)

[erker@xxxxxxxxxxxxxx (Greg Erker)]

Executive summary: the Stereo 225 aperture now goes
to f32 + 1/2 stop (~f38).

------

  The Ricohmatic 225 goes from f3.5 to f22
in 1/3 stop steps (clicks). Actually both of
mine go to one click past f22 (~f25).

  The Seikosha SLV shutters assemblies, when
removed from the camera, will stop down to
about f45. The stop in the camera that prevents
this is just the slot that the aperture control
lever moves in.

  It hits the end of the slot at f22+1/3. So by
lengthening the slot I should be able to get
f32 and perhaps more.

  One limitation is that the aperture lever
turns a geared ring that meshes with a 2nd geared
ring that surrounds the viewfinder lens. It
is used to display the aperture setting through
a window at the top of the viewfinder lens
bulge. Both geared rings only have teeth part
ways around. At f22 the last 3 teeth are in
contact. So I can't enlarge the slot so much
that the teeth completely disengage.

  So I gradually enlarged the slot (Dremel
cutting disk) and checked that I still had
enough mesh on the gear teeth. After a few cut
and check steps I had f32. I kept going
and got f32+1/3 but had to stop before f32+2/3
(last tooth was un-meshing). So I quit at
f32+1/2 stop.

  I was a bit worried that the last bit of
the aperture control arc wouldn't be "linear".
But the 3 clicks past f22 (which I call f32)
measure out to be twice the diameter of f16
(measuring curved sided pentagon with calipers
ain't easy :) .

----

  Needless to say, I'm a happy camper. I
always wanted a MF stereo camera with f32
and now I'll have that and more.

Greg