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'
Show the name and prominence of the mountains whose picture is not taken by a lens of brand 'Sigma'.
[Schema (values) (types)]: | mountain_photos |  mountain : id (text) , name (number) , height (text) , prominence (number) , range (number) , country (text) | camera_lens : id (text) , brand (number) , name (text) , focal_length_mm (number) , max_aperture (number) | photos : id (text) , camera_lens_id (number) , mountain_id (text) , color (number) , name (number);