Most of your editing work in Affinity Photo will be done in the Photo Persona. This is where you get the full range of adjustment tools, layers and masks, filter effects and more. But raw files are a special case. Raw files have to be processed, or ‘developed’ before you can work on them.
If you open a JPEG or a TIFF image in Affinity Photo, it will appear straight away in the Photo Persona. But if you open a raw file, it