When backing up photos form my Android phone i found that the phone didn’t present as a mass storage device, it would only appear as a MTP\PTP device and the file copy speed was terrible.
So some research led me to using the ADB command, you’ll need to enable USB debugging before this will work.
Find your files
adb shell ls /storage/
Back em up
adb pull /storage/self/primary/DCIM/Camera /home/user/photos/