Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.

### Instruction:

Convert text to sql: How many camera lenses are not used in taking any photos? | mountain : id , name , height , prominence , range , country | camera_lens : id , brand , name , focal_length_mm , max_aperture | photos : id , camera_lens_id , mountain_id , color , name | photos.mountain_id = mountain.id | photos.camera_lens_id = camera_lens.id | 

### Response:

select count ( _ ) from _ where _ not in ( select _ from _ ) | select count ( * ) from camera_lens where id not in ( select camera_lens_id from photos )