"Dave Blandston" <gra### [at] earthlinknet> wrote in message
news:39729613@news.povray.org...
| How do those darned things work, anyway?

A little more complex than you might think at first.  They are semicircle
leaves pivoting on both an anchor point and a sliding point.  The sliding
points are moved by a control which has notches to allow the sliding pivots to
go both inward and outward and also turn around the iris axis.  It's the
turning that makes it open and close, the sliding pivots allow for small
non-linear changes as they are moved.  And the leaves overlap in a screw type
way, only one end under the next leaf, not one on top of the other like a
regular layering.  That's how the iris on a old Kodak bellows camera I have
operates near as I can see anyhow.  I can't look from the other side without
tearing it apart completely because the shutter iris is broken.
If I can manage to make a rendering to show better I will, but don't count on
it.

Bob

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