How do I change from JPG to DNG in Photo?

Photos for Mac can read and import certain DNG files, but it can only convert any imported photos to TIFF, PNG, or JPEGs.

You will have to convert your files to DNG outside of Photos, before you import them to Photos, if you prefer DNG.

If your photos are already in the DNG format and you are asking how to pass them to external editors in their original format and not as JPEG, get yourself the "External Editors" extension from the AppStore. It allows you chose the file format when calling an external editor. I prefer it to the built-in "Edit with" command from the Image menu.

For example, when I open a DNG image with the External Editor extension from the "Edit" pane, I can select the source image format like this:

This will work, as long as you did not yet edit the image in Photos. If it has already edits applied, it will always be passed as a JPEG.

In Photos JPG is "in front" and DNG "underneath. Since I need the highest possible quality, I want to open the DNGs.

So you are shooting RAW-JPEG pairs?

When you import a RAW-JPEG pair, Photos will always use the JPEG as the original by default. You will see the "J" badge overlay on the thumbnail, if you enable "View > Metadata > Filetype"

You can switch to the DNG file as the original, but only if you open the photo pin Edit mode.

In the Editor the menu item "Image > Use RAW as original" will be enabled.

For example:

You have to do it for each of your RAW files individually. You cannot change the default, and there is no batch command to do this for all photos at once.

It might be easier to import only the RAW files at first, and the JPEGS only later, if you want to compare one of them to the RAW version.

2.if I follow your screenshot I cannot click "use RAW as original"......it is grey not black.....not clickable :-(

is your photo really open in Edit mode? In all other modes the "Use RAW as Original" will be grayed out.

Are your pairs showing the "J" badge? Photos is showing me all DNG files when I am searching for RAW.