How do you get OS X to use iPhoto on camera import instead of Photos?

Easy peasy. Just go to iPhoto preferences/General and set iPhoto as default import by checking that "Connecting camera opens" "iPhoto" in the option box. Then delete the Photos library which has gobbled up a ton of your memory by duplicating your iPhoto library.

Photos does not duplicate the library, it uses hard links to the iPhoto library.

Yes, Photos creates it's own library and the finder will say it's as large as your iPhoto or Aperture library.

No, it takes very little more space since, as a previous poster indicated, it references your existing images using hard links.

pmiles wrote:

No, Photos creates it's own Library.

That is incorrect, it uses Hard links so it appears to be the size of the items linked, but that is not the size it occupies, Google Mac Hard Link

This part is appropriate.

"You would typically use a hard link when you want a single file object to appear in multiple places"

Actually Photos does create its own library, complete with thumbnails, database files, etc. and hard links for the master/original files.

I am sure you are correct but my hard drive usage jumped by 85GB as I watched Photo set up and it went down again when I deleted the new library. I also appeared to have duplicates sync to my iPad Whic disappeared when I recynced. Can you explain? Perhaps I should play safe and migrate everything to Lightroom?

Old Toad wrote:

Actually Photos does create its own library, complete with thumbnails, database files, etc. and hard links for the master/original files.

That is what I said

it uses Hard links so it appears to be the size of the items linked, but that is not the size it occupies,

I am totally confused - you cant both be right! I tend to go with pmiles from my experiences. The photos library took 20 minutes or so to delete...

pmiles wrote:

No, it actually creates its OWN library. I know this to be the case because you can import photos into iPhoto and they are not put into the Photos library and you can import photos into Photos and they are not put into the iPhoto library.

That is correct, after you install Photos and set it as the default new photographs will not go to the iPhoto library (exactyly as expected) but the initial iPhoto library is represented by Hard Links not actual image files.

Believe what you want, it's your machine.

No, Photos creates it's own Library.

That is incorrect

I was taking this part of the post literally and replying to it. Tunnel vision.

PMiles:

Hard links are used in Photos to prevent duplication of media. You can verify that yourself by exporting some of your library to a small USB drive, enough to more than half fill the drive, then using Option Open to create a Photos library from the exported one. You'll note everything fits on the small drive. The use of hard links (multiple names for the same file) is what allows Time Machine to keep many many dates worth of backups without duplicating files that have not changed between dates.

Also, here's a quote from David Pogues's review: https://www.yahoo.com/tech/everything-worth-knowing-about-switching-to-os-x-1101 29491789.html

"What’s wild is that Photos accesses your existing photo library. It doesn’t convert the original photos into some new format. You’ll be able to switch back and forth among the three programs — iPhoto, Aperture, Photos — without having to duplicate any files or use up any more disk space.

There is one big catch, however: Your library splits at the moment you install Photos.

After you first run Photos, when you edit, add, or delete any pictures, those changes show up only in the one program you’re using at the time. New pictures you add to Photos appear only in Photos; new pictures you add to iPhoto appear only in iPhoto, and so on. (You can easily export/import them if necessary.) Same thing with edits you make: They’re saved only in the program where you make those changes."