Ran into the same issue and had to patch the code…
Here’s how I did it: http://ww.wp.xz.cn/support/topic/pinterest-setting
I had the same problem and has to patch the plugin code to use a higher resolution version of the thumbnail.
open wp-content/plugins/social-sharing-toolkit/social_sharing_toolkit.php in a text editor and change line 729 to:
if ($media = wp_get_attachment_image_src(get_post_thumbnail_id(get_the_ID()), 'full')) {
also on wp-content/plugins/social-sharing-toolkit/includes/share.widget.php, change line 20 to:
if ($media = wp_get_attachment_image_src(get_post_thumbnail_id(get_the_ID()), 'full')) {
just added an extra parameter to the wp_get_attachment_image function 🙂
Cheers
