547413 calling wordpress thumbnails

Hi Think this should be straight forward to anyone who knows wordpress. There are 2 tasks 1. add pinterest button to single posts 2. get opengraph og:images to work without a plugin I'm manually setting up opengraph using the following but it's only calling my main image 530px530px which I think is too big so need help calling the thumbnail. In [login to view URL]: function get_fbimage() { $src = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), '', '' ); if ( has_post_thumbnail($post->ID) ) { $fbimage = $src[0]; } else { global $post, $posts; $fbimage = ''; $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', [login to view URL]"> $post->post_content, $matches); $fbimage = $matches [1] [0]; } if(empty($fbimage)) { $fbimage = "images/[login to view URL]"; } return $fbimage; } Task is to either get this code to pull a thumb from my main post or an alternative way but I don't want to use a plugin. My blog is a simple photography site, each post has one photo and a little caption. Once accepted I will send you my theme and you can work from that. Feel free to ask any questions