Adding new cameras is very easy. You just have to know its crop factor, and the EXIF identification strings for this camera; that's all.

If you don't know the crop factor, you can search in google for e.g. “Nikon D300 sensor size”. Let's suppose you found out that your sensor size is 23.6 × 15.8mm. Now compute the length of the diagonal using Pythagora's theorem:

\[ d = \sqrt{23.6^2 + 15.8^2}\,\mathrm{mm} = 28.4\,\mathrm{mm} \]

Now you just divide the magic number 43.27 (the diagonal of a usual 35mm film frame) by the number you got:

\[ \mathrm{cropfactor} = \frac{43.27}{28.4} = 1.523 \]

Now you must find out the identification string for your camera from EXIF data. For this you can use the exiv2 script:

    $ exiv2 blah.nef
    ....
    Camera make     : NIKON CORPORATION
    Camera model    : NIKON D300
    ....

Now you can create a XML entry for your camera:

    <camera>
        <maker>Nikon Corporation</maker>
        <maker lang="en">Nikon</maker>
        <model>Nikon D300</model>
        <model lang="en">D300</model>
        <mount>Nikon F AF</mount>
        <cropfactor>1.523</cropfactor>
    </camera>

Now add this definition to a XML database file along lensfun database search path and your camera will be detected and lensfun will work properly with images produced by it.

Declaring cameras: <camera>