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Connect external storage devices to iPad - Apple Support
Direct import of photos from your camera SD Card to your Photo library is possible - subject to a couple of caveats:
- the SD Card must be correctly formatted as FAT, FAT32 or exFAT (FAT64)
- stored photos are stored within the expected DCIM folder
Import photos using Apple camera adapters - Apple Support
If you are unable to use the direct photo import feature, you should still be able to manually access and copy photos from the SD Card using the iPad’s built-in Files App. To do so, just open the Files App - and in the Sidebar you will see your SD Card in the list of Locations. If necessary, open the sidebar by tapping the sidebar icon at top-left of the Files App Window. Photos can be copied to the iPad Photo Library, or copied to a folder of your choice either on your iPad or elsewhere.