Good point about the rubber grip - they are easier to make for each prototype. I thought the scalloped rings were milled not cast, but it still requires more work...
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To me it would make sense to cast this geometri more or less complete and then finish off with milling/turning the ends and internals, with tight tolerances for large production volumes.
It takes a lot of machining to make these scallops and then engrave all of the meter and feet values all around the ring, would not make sense IMHO
That's also why I wonder why they did the prototypes with scalloped rings, but they could be engraved, maybe Rick can examine closely the engravings on the prototypes and compare with old normal pre Ai and Ai, Ais lenses,,,
It also looks like the numbers on old lenses are not directly engraved when you compare them to engraved lenses, modern lenses. One can see the material underneath the black paint bulges a bit like it's cast, not the distinct square look of an engraving.
Strip some old lenses for paint and let's see
I saw some 55mm 1.2 stripped from paint once,,,
