Transferring photos to an external drive

Transferring photos from your Late 2013 iMac running macOS Catalina (10.15) to an external drive is a straightforward process. You can use the built-in Finder application to accomplish this task. Here's a step-by-step guide:

1. Connect the External Drive:

Plug in your external drive into an available USB, Thunderbolt, or USB-C port on your iMac.

2. Format the External Drive (if necessary):

If the external drive is new or not formatted properly, you may need to format it to a compatible file system like macOS Extended (Journaled) or APFS. Keep in mind that formatting the drive will erase any existing data, so make sure you have a backup if needed.

3. Open Finder:

Click on the Finder icon in your Dock or press `Command + N` on your keyboard to open a new Finder window.

4. Locate the Photos:

Navigate to the folder where your photos are stored. Most likely, your photos are stored in the "Photos" app. If you have your photos stored in a different location, navigate to that folder.

5. Select Photos:

Click on the photos you want to transfer. You can select multiple photos by holding down the `Command` key while clicking on each photo.

6. Copy the Photos:

Once your desired photos are selected, right-click (or control-click) on any selected photo. From the context menu, choose "Copy" or press `Command + C` on your keyboard.

7. Navigate to the External Drive:

In the Finder window, locate your external drive under the "Devices" section in the sidebar. Click on the drive to open it.

8. Paste the Photos:

Right-click (or control-click) inside the external drive window, then select "Paste Items" from the context menu. Alternatively, you can press `Command + V` on your keyboard to paste the copied photos.

9. Wait for the Transfer:

The photos will start copying to the external drive. The time it takes will depend on the size of the photos and the speed of the drive connection.

10. Eject the External Drive:

Once the transfer is complete, make sure to properly eject the external drive before disconnecting it. You can do this by clicking the eject button next to the drive's name in the Finder sidebar or by right-clicking on the drive and selecting "Eject."

11. Verify the Transfer:

Before disconnecting the external drive, double-check that the photos have been successfully copied to the drive.

That's it! Your photos should now be safely transferred to the external drive. Remember to keep a backup of your important data, and make sure to follow proper ejection procedures before disconnecting the drive to avoid data corruption.

That depend.

Are the photos currently in a Photos library, loose in Finder folders, or arranged in some other way?

On the external drive, do you want them to be in a Photos library, loose in Finder folders, or arranged in some other way?

The answer could be as simple as copying the entire Photos library as a block or copying the separate Finder folders. It could be more complex if you want to change the format or arrangement.