I\'m able to get a picture-url from a specific facebook-post through the facebook graph-api (ie https://developers.facebook.com/tools/explorer?method=GET&path=19611830383339
Only users and pages have a pictureconnection – posts don’t. (A field is something different.)
But I guess the full_picture field is what you want: https://developers.facebook.com/tools/explorer?method=GET&path=196118303833398_362048290573731%3Ffields%3Dfull_picture%2Cpicture