Icloud keepts syncing 23,000 photos to new phone (16e).

It is possible for a Mac to have multiple Photos libraries. In this case, at most one library – the one designated as the system Photo library – can be synchronized with iCloud Photos. The other Photos libraries are strictly local.

So if you wanted to keep your 23,000 photos only on your Mac, and your Mac has enough storage for them, you might be able to do something like this (being very careful about the order in which you do the steps):

• Download full-resolution copies of all of your photos to your Mac (Download iCloud Photos and videos – Apple Support). (If you were using iCloud Photos with the "Download Originals to this Mac" option, you should have full-resolution copies already; but if you were using "Optimize Mac Storage", you want to grab full-size ones.)
• Quit Photos.
• Back up your Mac – including all of the photos that you just downloaded – to one or more external drives.
• On your Mac, turn off iCloud Photos on one device (the Mac) (How to turn off iCloud Photos – Apple Support), without deleting photos.
• Now you have a local library that contains all of your photos, and you've made a backup copy.
• Quit Photos.
• This step is destructive. Make sure you have downloaded and backed up your photos before doing it! On your Mac, launch Safari and sign in to iCloud through the Web interface (https://www.icloud.com). Go into the Photos interface, select all of your Photos, and trash them. Then go into the Recently Deleted folder to select them and trash them there. This will permanently delete all of your photos from iCloud and any device that still is synchronizing against it (which is why you must tell the Mac to stop using iCloud Photos first).
• Hold down the Option key while launching Photos to get the dialog for creating and choosing libraries. (Photos User Guide – Create additional photo libraries in Photos on Mac – Apple Support).
• Create a new library, say "Photos Synced With iPhone". Make it the current library.
• In Photos > Settings… (General tab), click on the "Use as System Photo Library" button to make the new empty library your System Photo Library. Do this before turning on iCloud Photos on the Mac, so that the Mac doesn't simply start uploading all 23,000 of your photos to iCloud!
• In Photos > Settings… (iCloud tab), turn on iCloud Photos. Now "Photos Synced With iPhone" (or whatever you called it) will synchronize with iCloud Photos (which is currently empty due to you having permanently deleted all of the photos in iCloud using the Web interface).
• Check that everything is OK and if so, back up your Mac again.

Now you have two Photos libraries:

• The original, which contains 23,000 photos – but is now a strictly local library
• The new "Photos Synced With iPhone" (or whatever you call it) one – which synchronizes with the Photos library on your iPhone (assuming you have iCloud Photos enabled on the iPhone, for the same Apple Account)

You can switch between them with the "hold Option down when launching Photos" trick.

It's not that you're doing something wrong-- it's that you are expecting iCloud to do something different that what it does. You can't have different pictures at iCloud Photos than you have on your device's Photos Library. That's not what iCloud is for.

iCloud Photos is a synchronization service. When you engage iCloud Photos on a device, then the Library on that device is kept exactly the same as the iCloud Photos Library. So, for instance, if you take a picture with your iPhone, it is added to the iPhone's Photos Library, copied to iCloud Photos Library, and then copied to the Photos Library on each of the other devices that you have connected. If you delete a picture on your Mac, then that picture is deleted at iCloud and on all the other devices. 

So you can't think of iCloud Photos as a backup service, since it backs up mistakes, and there's no way to undo them. Whatever you do with Photos on your device-- it happens everywhere else.

Because the Libraries are identical, you can use Optimize Storage on the Mac, on your iPhone, or on your iPad. If you set a device to "Optimize Storage," then Photos may store only smaller images on the device and rely on iCloud to keep the full sized images. Having screen-sized images stored locally allows you to quickly scan through your pictures while saving lots of storage space. And, if Optimize is chosen, and you want to Edit a picture, Photos will reach out to iCloud to get a full sized image for you to work on. Your optimized Library may take up less than 20% of the space of a fully downloaded Library. But an optimized Library may be kept larger than that if the extra storage space is not needed.

Beware, though: backing up a Mac Photos Library with Optimize Storage only backs up smaller images. If you want to keep a true backup on an external disk for safe keeping, you need to have Download Originals checked. If you don't have enough room on a Mac, you can backup an Optimized Mac Photos Library this way:

Backup iCloud Photos with an Optimized Mac

Does that clear up what's happening?

If you are not using iCloud Photos, there is the option of transferring photos from your iPhone to a Mac or Windows PC using a USB cable.

Transfer photos and videos from your iPhone or iPad to your Mac or PC – Apple Support

However, if you are looking to automatically back up photos on your iPhone, there are basically two ways to do that: synchronizing to iCloud Photos, or making automatic iCloud backups that include photos. If you do not use iCloud Photos, and you exclude photos from iCloud backups (or do not do iCloud backups at all), that puts the burden on you to remember to back up photos manually on a routine basis.

This is the most complete and helpful information I have ever received on backing up photos to external hard drives using full resolution. I need to add one more step however... because the photos I need to put on the backup drive are on an old iPhone I need to erase and turn in.

Would I be able to go directly to a folder on the external hard drive and still retain full resolution photos and videos? Currently they are "optimized" on this phone I believe so there I go adding another step correct?

Musicplayingwrongspeeds wrote:

This is the most complete and helpful information I have ever received on backing up photos to external hard drives using full resolution. I need to add one more step however... because the photos I need to put on the backup drive are on an old iPhone I need to erase and turn in.

Would I be able to go directly to a folder on the external hard drive and still retain full resolution photos and videos? Currently they are "optimized" on this phone I believe so there I go adding another step correct?

If that phone is using iCloud Photos, with "Optimize iPhone Storage" turned on, there are several points that you may want to consider.

1. There might not be enough device storage on the phone to download full-size copies of all of the photos to the phone. I would suggest verifying that there is enough storage (with room left over) before turning off "Optimize iPhone Photos" so you do not fill storage with a partial photo database, and potentially run into other issues.
2. I do not know what your iPhone will do (as far as exporting full-size copies vs. thumbnails) if you export photos to a directly-attached drive while "Optimize iPhone Storage" is on (or the phone is still processing turning it off).
3. It should be possible to get to the full-size photos onto a computer by logging into the https://www.icloud.com/ Web interface, with the Apple Account you are using on the old iPhone, as long you have enough iCloud space that iCloud Photos has not stopped synchronizing photos for lack of room.
4. I believe that if you follow Apple's instructions in What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support, this would not erase full-size photos and videos in iCloud. You could theoretically get rid of the phone and then retrieve your photos.
5. Deleting the photos from the Photos app on your old iPhone while it was still synchronized to iCloud would be catastrophic, because those deletions would synchronize.
6. If you are moving photos outside of the Photos system (either by downloading from iCloud, by using the Mac's Export options, or similar means), note that each "photo" in Photos might actually consist of an original version and an edited version. This doesn't translate directly to other systems, so if you want the ability to "revert" an exported, edited photo, you might need to export/save both the original version and the edited version.

opalyho731 wrote: …Thank you very much. This explanation is helpful.

Glad to help. We're here if you have more questions…

Thank you so very much

You’re welcome.