Axiom 50 f/1.4

What this demo is doing

Nine blades pinned at the barrel wall, each swinging about its own pivot - the same linkage a real iris uses. Pick an f-stop and the page solves backwards for the blade angle that produces that opening, then clips every blade against the bore as it turns. The rounded nine-sided hole you get at f/11 is a consequence of the mechanism, not a texture.

The front element is coated glass, so it does two things at once: it mirrors the softboxes overhead and lets you see the iris sitting behind it. The violet-to-green cast across the glass is the multi-coating, strongest at the edge where light strikes at a steeper angle.

Focus is mechanical too. Rack to 0.45 m and the front group extends on its helicoid while the engraved distance scale turns under the red index mark.