How to sync a non-system photo library to iPad?

Long Shot: Try going into Photos and making the non-System library that you want to synchronize to the iPad, the current Photos library. Then quit Photos and see if Finder offers to do the synchronization that you want it to do.

(Finder obviously has some way to access the Music, TV, and Photos databases – despite those three applications supposedly being separate. So maybe, if it doesn't have its own library selection controls, it is picking the "current library" selections from each of those programs.)

Servant of Cats wrote: … I don't think that the OP is asking how to synchronize two Photos libraries, using iCloud, for the same Apple ID.

oh… darn!

In that case, in spite of concerns otherwise, I would, on the Mac, turn off iCloud in the System Library, and then make the Alternate Library the System Library. Then, keeping iCloud turned off, I'd do the usual cable stuff.

As far as iCloud.com is concerned, the Mac just lost power, or went in tunnel--things it's used to. If you're nervous, you could turn off WiFi entirely.

When you're through, switch the System designation back to the original Library, turn on iCloud, and iCloud.com sees you coming out of a tunnel.

Getting the switching mixed up could throw iCloud.com for a loop, of course, so, as Matti says, backups are in order!

The system Photos Library is intended to be the central library that is visible in other apps and can be synced to other devices. It would help to keep all photos that you want to sync to other devices in your system photos library and to remove alleles important photos to your other libraries.

My system Photos Library is holding just the selection of photos that I am frequently using. There are many separate smaller libraries with all my photos on external drives. occasionally I am importing photos from these archive libraries to the system photos library, when I need them for a project. I like to use PowerPhotos to move selected albums between my libraries.

Servant of Cats wrote:

Long Shot: Try going into Photos and making the non-System library that you want to synchronize to the iPad, the current Photos library. Then quit Photos and see if Finder offers to do the synchronization that you want it to do.

I'd be very careful to first make a local verified full backup of the Photos library (to an external volume, for example) before doing anything in case something unexpected happens.

AFAIK the library must be set as a "System library" before it can be synced to iCloud or via Finder to an iPad. And wouldn't such a change cause iCloud to start replacing the "old" library with the "new" library to iCloud? I have not much used iCloud Photos and I have mainly synced via the Finder and USB to an iPad so correct me if necessary.

One alternative is to export the photos to a folder in iPad Files.app either locally to "On My iPad" or to "iCloud Drive" and browse them there. I have used both methods. They do not offer the same features as Photos library but get the work done. Then the iCloud Photos can be browsed via the iPad Photos.app.

iOS and iPadOS devices each have only one Library. There is only one Library at iCloud.

So no, you can't sync two Libraries, and you can't sync aLibrary with iCloud if it's not the one designated as the System Library.

Richard.Taylor wrote:

iOS and iPadOS devices each have only one Library. There is only one Library at iCloud.

So no, you can't sync two Libraries, and you can't sync aLibrary with iCloud if it's not the one designated as the System Library.

I don't think that the OP is asking how to synchronize two Photos libraries, using iCloud, for the same Apple ID.

The OP said "iCloud is turned off on my iPad. So I just want this [non-system] library synced to iPad manually."

Logically speaking, I can't think of any reason to prohibit this type of synchronization, as it does not involve any duplication of the synchronization that iCloud Photos is doing. But it's an unusual corner case, and it's possible that iTunes (pre-Catalina) and Finder (Catalina and later) simply are not set up to deal with it.

Matti Haveri wrote:

AFAIK the library must be set as a "System library" before it can be synced to iCloud or via Finder to an iPad. And wouldn't such a change cause iCloud to start replacing the "old" library with the "new" library to iCloud? I have not much used iCloud Photos and I have mainly synced via the Finder and USB to an iPad so correct me if necessary.

I was not suggesting setting the secondary Photos ibrary as the System library! If changing the System library designation is a requirement for doing a manual synchronization, the OP should not attempt it. I agree with you that changing the designation of the System library would have very unwanted effects.

I was suggesting setting the secondary Photos library as the current Photos library. Making it the current library (the one that Photos opens when you launch it without holding down Option) would not affect the System versus non-System designation.

Making backups is a good idea in any event.

Before I started using iCloud, I switched my System Library designation around quite often, because I had multiple Libraries for which I wanted to use an app that only worked with the System Library. (Luckily, Apple let them fix the app!) Now, like for léonie, my System Library is a smaller Favorites Library. (In fact, I got the idea from her.) This would be a great solution if you are just wanting someplace to see all your favorite pictures, but you have too many others clogging the works.

But if you really want two devices with two different Libraries, then the only problem I see with swapping System Libraries is with iCloud, and if you turn off iCloud, then Photos at iCloud.com will never know. But you do have to be careful with the switching. Turning off both WiFi and iCloud Photos should be good redundancy. Backups is also a good plan.

alafortanfuni wrote:

Through Finder, I can choose a folder located on my mac and sync photos to iPad from there. But I wanted to create a separate Photos library which is not connected to iCloud (both the iPad and the photo library is not connected to iCloud) and sync it. Instead of dealing with folders I would edit photos, make albums etc. on Photos app and easily sync it (Like we did before the iCloud service was introduced.)

Yes, I guess syncing a Finder folder to an iPad should preserve the concurrent Photos "system" library that is synced to iCloud or via Finder and USB to iPad.

p.s. In the past I have synced only an empty Finder folder to iPad as a means to empty it from previously synced system Photos library. With 40 000 images that takes surprisingly long time and sometimes the sync must be repeated if it times out until all the old synced images are cleared off.