I just got this e-mail response from Phil Harvey, the author of EXIFTools. He makes a good point about including the purchase date into the mix. If anyone wants to provide same, I'll put the data together for Phil and maybe we all can sort this out!
Phil's reply:
Hi Curt,
Thanks for the email. This is very interesting.
These tag names are my best guess at what the information could mean, but with the help of people like you we can perhaps nail things down a little better. I can add 2 more samples to your list, from my friend's K10D and my own:
ManuDate Purchase Rev S/N
20061021 20061202 1.2 3383102
20070913 20071022 2.1 132352
Here the second date is the purchase date, which in both cases is about 5 weeks after the "ManufactureDate" in the camera. Because of this, I don't think it could be a date inside a component, since 5 weeks is already not much time to deliver the camera to a retailer in Canada after manufacture. But I don't know much about manufacturing, so perhaps this is still possible. We both ordered our cameras, so they didn't spend any time sitting around on retail store shelves.
I can't, however, explain the really early dates. Also, the internal serial number seems unique for each camera, but doesn't increment sequentially as you mention. It is possible this is encoded, as a few of the other Pentax tags have been (ShutterCount and the FirmwareID tags). Your data for the ModelRevision tag is also interesting, but again I'm not sure what this means.
It would be interesting to collect even more data if possible, with purchase dates too. If any of the values are encrypted we may start seeing a pattern.
- Phil
FWIW, here is my 'augmented' data:
20051201, 20070504 (May 4th, 2007), 1.5, 5097223
Does anyone have an inside contact at Pentax???
Curt