CREATE TABLE mountain (id DECIMAL, name TEXT, height DECIMAL, prominence DECIMAL, range TEXT, country TEXT)
CREATE TABLE camera_lens (id DECIMAL, brand TEXT, name TEXT, focal_length_mm DECIMAL, max_aperture DECIMAL)
CREATE TABLE photos (id DECIMAL, camera_lens_id DECIMAL, mountain_id DECIMAL, color TEXT, name TEXT)

Show the name and prominence of the mountains whose picture is not taken by a lens of brand 'Sigma'.
SELECT name, prominence FROM mountain EXCEPT SELECT T1.name, T1.prominence FROM mountain AS T1 JOIN photos AS T2 ON T1.id = T2.mountain_id JOIN camera_lens AS T3 ON T2.camera_lens_id = T3.id WHERE T3.brand = 'Sigma'
SELECT "name", "prominence" FROM "mountain" EXCEPT SELECT "T1"."name", "T1"."prominence" FROM "mountain" AS "T1" JOIN "photos" AS "T2" ON "T1"."id" = "T2"."mountain_id" JOIN "camera_lens" AS "T3" ON "T2"."camera_lens_id" = "T3"."id" AND "T3"."brand" = 'Sigma'