private function getCameraModelsByAuthor() {
        
        $query = 'SELECT CONCAT(camera_make, " ", camera_model) AS `key`, COUNT(*) AS number, href FROM (
            SELECT DISTINCT e.camera_id, i.user_id, c.make AS camera_make, c.model AS camera_model, CONCAT("/photos/cameras/", c.url_slug) AS href
            FROM image_exif AS e