$c = new Criteria();
    $c->addJoin(PropertyPeer::REFERENCE, ImagePeer::PROPERTY_REFERENCE, Criteria::LEFT_JOIN);
    $c->addSelectColumn(ImagePeer::THUMBNAIL_FILENAME); 
    $pager = new sfPropelPager('Property', sfConfig::get('app_pager_list_max')); 
    $pager->setCriteria($c); 
    $pager->setPage($this->getRequestParameter('page', 1)); 
    $pager->init(); 
    $this->property_pager = $pager;