It should be, at least theoretically, possible to convert one RAW digital image format to another with some professional digital photo editing program. So a Fuji RAF to Nikon NEF conversion might be possible.
Convert Fuji CCD-RAW graphic image to Nikon Digital SLR camera RAW image.
We have found 9 software records in our database eligible for .raf to .nef file format conversion.
Microsoft Windows software - convert raf to nef on Windows
Adobe's professional tools for RAW image management and post-production
Convert from raf file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned raf to nef. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Program used to manage pictures and photos
One of the best bitmap graphic editing program
Fast and inexpensive app for creating impressive landscape images
A complete image retouching program
Photo Manager is digital photo editor and manager for Windows
Apple macOS / Mac OS X software - convert raf to nef on OS X
Mac version of Adobe' professional digital photo editing tools
Mac version of popular digital image editor
Apple Aperture is photo editing and management software for Mac OS X