First you need ExifTool, you can download it for free from here: http://www.sno.phy.queensu.ca/~phil/exiftool/
- Unzip it to a folder, e.g. c:\program files\exiftool – on Mac you start the installer, exiftool will then be installed to /usr/bin.
- Now copy the pictures from your memory card into a temporary folder, e.g. c:\temp\convert on Mac for example ~/Convert
(do not do that on the original pictures, always use a copy!)
- Open a command prompt (Mac: a terminal session) and switch to the directory with the pictures.
Windows: cd c: \temp\convert
Mac: cd ~/convert
- Now let ExifTool write the model name of the D850 into the pictures.
Windows: c:\program files\exiftool\exiftool.exe -model=”NIKON D850″ *.NEF
Mac: /usr/bin/exiftool -model=”NIKON D850″ *.NEF
That’s it. Exiftool writes the new camera identification in the metadata. The original file is kept for security with the suffix _original.
For safety’s sake you should, as I said, keep the original images so you can replace them later, as soon as Lightroom officially supports the camera.