Do shooters use their lens or just talk about them?

Some absolutely swear by the Vivitar Series 1 lenses, but that may be too general a statement, some swear by THEIR copy, but many can be found on Ebay at low pricing, unlike many lenses for Nikon F, while it is generally hard to find Nikon F mount lenses selling for 'bargain' prices, meaning good condition for low ish pricing, moreso difficult than most other brands.

But again, may it is sample variation or difference in manufacturer, as Vivitar was known to use many, the serial number should tell you.

Kiron serial numbers start with 22... and Komine 28... Tokina 37..., the others made by such as Cosina did not seem to have much of a reputation. Does yours start with any of those three or something else?

The lens that would be interesting to test is the Vivitar Series 1 200mm f3. Although seems hard to find on Ebay.  I was once on the verge of buying a Vivitar 28mm f2 Close Focus made by Komine. But waited instead for a reasonable priced 28mm 2.8 AIS.

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.....Just from an amateur......''Sometimes it's to your advantage for people to think you're crazy.”