@scottbb surely the shape rotates but leafs are not rotating, it's only the shape which they form which is rotating. Basically one can create oval iris shape easily, the leafs would be placed in oval shape and the directing grooves on the iris should be designed to keep oval shape.
@Expotr oval aperture is the same as round aperture except initial leafs placement and grooves.
I think the image of the week is great, and I often see an image that I would like to know more about, or see in a larger size. I expected that clicking on the image would take me to the original entry, where the photographer might have made some notes of what the photo is of and how/where it was...
@EuriPinhollow re: rotating opening vs rotating blades: yes, thank you for the clarification. That's exactly what I meant.
@Expotr the thing is, when you stop the aperture down, you begin losing the bokeh you're looking for. Also, if you'll notice in @EuriPinhollow's image, as you stop down, the shape becomes more polygonal (straight-sided) and less rounded. This is unavoidable with an iris aperture.
For the anamorphic-like oval bokeh, you want the ovals to stay vertical, and they probably need to stay smooth, not ovoid-polygonal. I think it would ruin the look (which after all, just comes from the horizontal compression of an anamorphic lens)
@Expotr also, when stopped down a bit, the piecewise-continuous oval-shaped polygon would create diffraction spikes (multi-sided stars) rather than the smoother glare that anamorphics are known for. Diffraction spikes aren't bad per se (it's a matter of taste), but they are not an accurate replacement/simulation of a real anamorphic lens.
Its been a while since I've had time to make any tutorials but going to try and find time this weekend to do one. Conference / Travel season for me starts next week so want to get at least one or two in before then.
@EuriPinhollow absolutely, rounded blades help cancel polygonisation. At the widest possible setting, the aperture can be perfectly round. But as I said, as you stop down polygonisation starts to set in. At large f-numbers, even with curved blades, the aperture looks more like a polygon than round, as far as diffraction spike -generation is concerned.
@EuriPinhollow BTW, that iris you linked to is beautiful. It's a shame they couldn't squeeze just one more blade in there though (it has an even number of blades). If it had 17 blades, the diffraction stars would be gorgeous!