Vivitar Macro Addendus

[SATCHMO]

1 - Both the Ser. 1, 90mm/f2.5 and the 90mm/f2.8 ceased production in Oct.,
1979.
2 - The 90mm/f2.8 contains 6 elements. Joe Canon Arnold

[Mario Raspanti]

And I have still another model!
It is a 90mm macro; it is non-series 1; yet it is f2.5, not 2.8.
It is engraved "Vivitar 90mm 1:2.5 MC Macro Telephoto No.28600621 o62mm"
around the front element, and just "Lens made in Japan" near the mount.
It is 85mm long (from the mount) when focused to infinity; while
focusing up close, the lens "expands" on both sides of the focusing ring
(which rotates a full 2 and 2/3 turns) and grows to 177mm, reaching 1:1
magnification without accessories.
Someone knows anything about this lens? Who made it, when, and so on?

Which leads me to another question. I have sometimes overheard delirious
discussions on how a Summarit compares with a Summicron, how much German
Zeiss lenses are better than Japanese ones, and so on; several books
detail how many variants of how many lenses these firms ever made. I am
aware than Vivitar is not Leitz, yet some of the older Vivitars (made by
Kino Optical, Perkin Elmer and the like) seem to be very fine pieces of
equipment. Is there nobody able and willing to write down a sort of
history of the Vivitar production?

Mario