How many distinct kinds of camera lenses are used to take photos of mountain ranges in the country "Ethiopia"?
select count ( distinct t2.camera_lens_id ) from mountain as t1 join photos as t2 on t1.id = t2.mountain_id where t1.country = 'Ethiopia'
What about in other countries?
select count ( distinct t2.camera_lens_id ) from mountain as t1 join photos as t2 on t1.id = t2.mountain_id where t1.country ! = 'Ethiopia'
What are the names of the photographers who used those lenses?
select t1.name from mountain as t1 join photos as t2 on t1.id = t2.mountain_id where t1.country ! = 'Ethiopia'