Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE mountain ( id number, name text, height number, prominence number, range text, country text )
TABLE: CREATE TABLE photos ( id number, camera_lens_id number, mountain_id number, color text, name text )
TABLE: CREATE TABLE camera_lens ( id number, brand text, name text, focal_length_mm number, max_aperture number )

### Question ###
How many different kinds of lens brands are there?

### Accurate SQL ###

SELECT COUNT(DISTINCT brand) FROM camera_lens