The Eames’ Polaroid SX-70 film https://youtu.be/Lo_1pyQ7xvc has a technical summary, as well as probably being the inspiration for Steve Jobs’ magical-revolutionarist mode of marketing.
The scans of the photographs at the end of the article are illegible. I do wonder if the aperture's gradual opening/closing results in Gaussian-like defocus bokeh and tapered-off motion blur (in the presence of defocusing, spatially tapered like a CRT).
Do we even have the kind of engineers that could design, develop, and produce something like the SX-70 today? It really was a marvel of insanely clever design - the mechanisms, optics, batteries, film, flash, etc., all produced at a price that was only a bit higher than conventional photography and processing, and offering unparalleled convenience. (As well as, of course, instant gratification!)
Interestingly, the smooth bokeh has become a bit popular and is available with Canon "defocus smoothing" lenses (among other older examples). Rather than varying the aperture size over time, these just have a ND filter with the aperture window function coated on (and also a normal iris - the effect works best at the largest aperture setting).
Is it unusual though? I have several toy cameras with similar "overlapping circle" shutters, and a medium format Mamiya with a focal-plane leaf shutter where "the iris and the shutter are the same" practically speaking, which differs only from the sx-70 in the shape of the effective iris at the start and end of the exposure.
There’s a big difference between a leaf shutter, which isn’t unusual, just old fashioned, and actually making the shutter and aperture one and the same mechanism.
What model is your mamiya? Leaf shutters are not normally (by definition, I thought) focal plane shutters. That sounds really interesting!
The Olympus PEN cameras (and subsequent small cameras by olympus) have a in lens shutter that is simply two blades. The blades have a triangle cut out of each side and form a diamond shaped aperture. In this shutter the shutter blades form the aperture. This design is from at least 1959 with the release of the PEN.