If you're moving from Aperture to Photos for OS X, the first thing you'll need to do is import your library.
Apple's pulling the plug on future Aperture development. It still works with OS X Yosemite, but Photos for OS X is the future. Luckily, importing your existing Aperture library is easy. You can either do it during initial setup and make it your main Photos library, or you can import it at any time and make it an additional library. Once you've imported your library into Photos, you can still use the old version in Aperture. They won't stay in sync from that point on, but they will both remain accessible to their respective apps.
How to import your Aperture library into Photos for Mac
If you want your existing Aperture library to be your main Photos library, simply select it as part of the initial setup.
If you want to import your Aperture library as an additional Photos library, here's how.
- Locate your Aperture library in the Finder. The default location is in the Pictures folder.
- Hold down the control button on your keyboard and click on the Aperture library (or right-click).
- Select the Open With menu and and click on Photos.
- Photos will now launch and will import the Aperture library. Once it's completed, all your Aperture library photos will be there.
Using Aperture with Photos for OS X
Photos isn't a replacement for Aperture. Aperture has a lot of sophisticated editing features, support for external editors and a host of other capabilities that Photos just doesn't do. What's more, Apple has offered assurances that even though Aperture isn't available for separate, new sale any longer, the app will continue to work with OS X Yosemite, so you can be assured that it won't die right away.
If you really want to move to Photos, but you want to keep using some of Aperture's features, the good news is — you absolutely can. After import, your old Aperture library remains intact. OS X identifies the Aperture library as having been imported into Photos, and if you try to open it in Aperture, you'll get a warning. You can, however, open it anyway. Just be aware that if you do additions or edits, they will not carry over to the imported Photos library.
Personally, I've found that Photos cooperates well with Aperture. I actually use them both together: Because Photos has such great integration with iCloud Photo Library and works so well with my iPhones, it's become my primary image importing tool, but I prefer to work with Aperture for color correction and editing. The Add to Aperture option from the Photos share sheet lets me export the images I want to work with in Aperture quickly and easily.