Moving imported photos to external drive
I was looking for an intuitive "grandma could do it" GUI solution, but I ended up doing:

find / -iregex '^.*\.cr2$' -exec zip cr2.zip {} \; -delete 2&gt;/dev/null


Then used the GUI to click &amp; drag the .zip archive to the external USB HDD, mounted at /Volumes/disk2/. 

Looks like all the images imported directly from the DSLR are stored in ~/Pictures/Photos\ Library.photoslibrary/Masters/. So in hindsight; to target the specific directory, instead of searching the entire filesystem, I would input the relevant path:

find ~/Pictures/Photos\ Library.photoslibrary/Masters/ -iregex '^.*\.cr2$' -exec zip cr2.zip {} \; -delete 2&gt;/dev/null


Or even better, eliminate the need to click and drag by including the destination path as well:

find ~/Pictures/Photos\ Library.photoslibrary/Masters/\
-iregex '^.*\.cr2$'\
-exec zip /Volumes/disk2/cr2.zip {} \;\
-delete 2&gt;/dev/null




Or simply mv rather than zip:

find ~/Pictures/Photos\ Library.photoslibrary/Masters/\
-iregex '^.*\.cr2$'\
-exec mv {} \; /Volumes/disk2/ 2&gt;/dev/null