Nikon D7000 firmware version numbers A, B, L

Question

When I look at the firmware versions in the menu of my Nikon D7000, it shows three different version numbers: A, B, and L. This is no surprise, as they are clearly documented in the user manual, but without explanation of why there are three of them and what they mean.

When I update the firmware using the latest package from Nikon's website, the download specifies only the A and B version numbers. And when the update is done, the L version number has not changed (for me anyway).

My buddy also has a D7000, and as far as we can tell the two are identical, except that the L firmware version is different on his than on mine.

So what does all this mean? Is it Lens firmware specifically for interfacing to CPU lenses (but if so, why is it not subject to updates)? Is it "bare metal" firmware burned into a chip in the camera that can't be changed?

And finally, is there any possibility of different behavior of any kind from two otherwise identical cameras with identical lenses and settings, but different L firmware versions?

Answer 1

The L firmware is a lens distortion/correction database, and it is updateable. You can find the latest updates here.

Yes, it would be limited to lenses that can identify themselves to the camera (and only Nikon lenses, I'd think). If you are shooting RAW and use a RAW converter, such as Lightroom or Adobe Camera Raw, that has its own distortion correction database, then there's no real reason to risk a firmware update. A firmware update is always risky, just as a BIOS update on a motherboard would be, since if the process fails mid-stream, the camera may no longer realise it's a camera. The lens database shouldn't cause bricking, but it may affect the camera's POST (power-on self-test).