How to turn an Album into a Slideshow and Preserve the Sorting, 2019 Version
Update for Photos 5 on macOS 10.15.4 Catalina: Thanks to Old Toad for pointing out the change:
In the most recent version of Photos 5 the sorting of the photos will be preserved, if we collect and arrange the photos in an album and then select all photos in the album at once with ⌘A. Then use the command "File > Create > Slideshow" or the contextual menu (right click or ctrl-click the selected photos) and use "Create > Slideshow". The resulting slideshow will preserve the sorting of the selected photos.
In Photos 3.0 on High Sierra and Photos 4.0 on Mojave:
When you use the file menu to create a slideshow from selected photos, the resulting slideshow may have a different sorting.
Try to create the slideshow from the contextual menu instead of from the file menu.
- Select the sorted album with the photos in the sidebar.
- Ctrl-click or right click or tap the album with two fingers.
- Now select "Create > Slideshow"
For some reason this will preserve the order (at least for my albums in Photos 3.0) while using the file menu will not (the screenshot below is from Photos 3.0).
It is not easy to rearrange the photos once they are in the strip with the slides. The more elaborate slideshow themes have a fixed order of templates, and Photos wants to select the photos in a way best fitting for the predefined templates. I am only using the slideshow themes with just one photo per slide, Ken Burns and Classic. That has the added benefit, that the animations will not distract the audience from watching my photos.
I found this solutions in one of the discussions here, posted by the user pawey47 :
Re: How can I sort slideshow photos chronologically?
This user tip was generated from the following discussion: Photos slideshow changes order of photos
Previous, deprecated version: How to turn an Album into a Slideshow and preserve the sorting