'slide' );
$loop = new WP_Query( $args );
if ( $loop->have_posts() ) : while ( $loop->have_posts() ) : $loop->the_post();
$image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID, "best_cover", true), 'bestcover');
?>
Setup your slides in the admin area by using the "Slide" custom post type, we'll take care of the rest!