When exporting Sony .ARW raw files (taken on a Sony NEX 5) as JPEGs from the latest version of Lightroom classic CC the resolution is reduced e.g. a file which was originally 3500 x 2666 pixels produces a JPEG of 1486 x 1951 pixels! This is NOT a case of my accidentally having ticked the resize option in the export dialogue box; when I export JPEGs from my Canon raw files I don't get the same problem.
It occurred to me to try the "edit in Photoshop" option on the "photo" menu to see if producing the JPEGs from Photoshop would work but this option was greyed out (again, only in the case of the Sony raw files, not Canon).
Any comments/suggestions welcome!
That was it - should have spotted it myself! Many thanks for your help.
Glad you got it sorted. A better user interface would have warned you when you tried to export or edit in PS.