I was curious how a camera's diaphragm shutter works, so decided to make one in NodeBox.

NodeBox is great for projects like this because it allows you to feel your way through a problem, trying different blade shapes, positions, polygons, sizes, rotation points, etc. until you get it just right.

The attached network contains two different versions, both set up for animation. The first shows the entire shutter mechanism. You can adjust the lens size and number of blades then start the animation to see the aperture opening and closing. The animation starts with a closeup on the lens itself then pulls back and, when everything is in view, adds more blades.

The second network demos two subnetworks, shutter and lens_clip, that are polished and ready for you to use In your own projects. The shutter subnetwork lets you set a lens size and position, aperture from 0 to 100, and number of blades from 5 to 12. Len_clip takes whatever shape or shapes you wish to "photograph" and clips them to the outline of the shutter. The demo shows the lens following an S-shaped path around a simple mountain and lake scene, opening and closing as it goes.

Feel free to explore both networks to see how they work. There were a few interesting problems to solve like creating the illusion that the blades were interwoven (the bottommost blade covers part of the topmost blade). The clip sub-subnetwork inside lens_clip clips a scene without losing the fill colors. The animation requires only a few nodes but creates a complex, multipart choreography.

Network with screenshots and animated GIFs attached. Comments welcome. Enjoy!

John