Hi,
I've found this intersting forum because of the link to my website. (LensID information) [2]
Since I don't know much french I try in english, I hope some can read it ;-)
I maintaing a big list called extended LensID, it's use is to identify various CPU lenses exact
and to differenciate between Nikkors and 3rd party lenses. This can't always be done by focal length,
take the 12-24/4 as an example.
Seems to some new research on Nikon CPUs and lens data transferred to the camera.
I did some research some time ago with the varous patent info published by Nikon.
I also read some lens data with the help of an oscilloscope to find the LensID and fix
information that classifies a lens. This is mainly info that doesn't change with TC's and zooming.
This info and even more is recorded in EXIF makernote tags, and now used by some poplar EXIF readers.
The info I use is coded at addresses (0x12 to 0x18) the the bytes have following meaning:
ADR NAME DESC
0x12 LensID An unique ID to identify a Nikkor lens (misused by some 3rd party lenses)
0x13 AppStops The number of aperture stops a lens has, coded in 1/12th steps
0x14 FocLengthShort Focal length on the short (wide) zoom end, coding can be found in [1]
0x15 FocLengthLong same for the long (tele) end
0x16 MaxAppShort Max apperture value on the wide side, coding see [1]
0x17 MaxAppLong same for the long (tele) end
0x18 MCU_Version This byte identifies the CPU chip. One chip was used for up to 4 lenses in
the beginning of the AF aera. The lens is selected by bridges on the flex board.
Actual focal length is transmitted in 0x10 and the effective apperture is at 0x19.
With 'D' lenses the distance information is transmitted in byte 0x0D, coding also in [1]
I you have a look on the table containing the lensdata posted at this site [3], you find this correlation. (image below)
If you want to make 'P' chips you have to collect much more data and examine the data of 'P' lenses.
Then you have to find a suitable uC, a PIC with SPI may do the job, but I don't know.
The hardest part is to get your uC connected. Contact blocks are not easy to get ...
I hope I could help you a bit. Maybe you have some lenses missing on my list [2], so pleas help
me to fill the gaps.
Robert
[1]
http://members.aol.com/khancock/pilot/nbuddy/[2]
http://www.rottmerhusen.com/objektives/lensid/thirdparty.html[3]
http://www.nikonpassion.com/modules/smartsection/item.php?itemid=83