Good question. Apple's new Photos app looks set to revolutionise how people use photographs in Mac OS X, but not everybody is looking forward to Photos. Keen users of Apple's powerful iPhoto software want to know if they will be able to keep using iPhoto after Photos launches.
For some people the switch from iPhotos to Photos is chilling because they have spent many years building up a well-organised image collection in iPhoto. Now they are faced with learning a whole new app and migrating all their images to a different place.
Photos is set to simplify the process of viewing, and editing, images in Mac OS X. For many people this will be great news, because it brings the ease-of-use from the Photos app from iOS to the OS X environment. But for a lot of other Mac users the switch from iPhoto to Photos is set to be a huge, and unwelcome, downgrade. There are far fewer image editing options in Photos than in iPhoto.
See also:
Apple Photos for Mac OS X release date rumours
Mac OS X Yosemite vs Mac OS X Mavericks comparison
14 photo-sharing tips for Mac OS X
How to transfer photo libraries from iPhoto to Photos
Photos is currently available as part of the OS X Beta Program. It is delivered to Mac OS X alongside the OS X Yosemite 10.3 Public Beta, rather than as a standalone app that you get from the App Store.
This suggests that Photos is set to be delivered to all Mac OS X users whether they want it or not.
Migrating your photo library from iPhoto to Photos is certainly easy enough. Just launch the Photos app and it will automatically migrate your entire iPhoto library. According to Apple: " your photos, videos, projects, albums, and so onwill automatically appear in Photos upon launch. Some metadata, like star ratings and flags, will be transformed into keywords, so you can easily search for them. iPhoto Events will be turned into albums, which you'll find in an iPhoto Events folder in the Albums view. Photos uses the same master files as iPhoto, so you won't need double the space to run both apps."
Can I still use iPhoto after migrating to Photos
Yes, just launch the iPhoto app as normal. When you migrate to Photos it creates a separate photo library, but both apps share the same master photos from the migration. However, from that point on any changes you make are only reflected in that app. As Apple says " You can still use iPhoto, but any changes or edits you make there will not be reflected in Photos. And any changes or edits you make in Photos will not be reflected in iPhoto."
When you launch iPhoto you'll be presented with an alert. The alert says "The content of this iPhoto library already has been migrated to the Photos app. This library can be opened in iPhoto, but any changes, including importing new photos, will not appear in the Photos library".
Click Open library in iPhoto to carry on using the iPhoto app as before, or Open Photos to quit the iPhoto app and open the Photos app (or press Quit just to quit the iPhoto app).
This is good news for people who want to carry on using the iPhoto app, although it still doesn't bode well in the long-term. While we expect iPhoto to continue running on Mac OS X for many years to come, we have no idea if Apple will keep iPhoto on the Mac App Store, and we don't expect many updates beyond ensuring it works with future operating systems.
So don't chop and change between apps, move to Photos when you are ready.