Hmm… your using ACF4… ACF5 has the option. I guess that needs to be thr first follow up question now (what version are you using 😛 )
First thing you should do is to turn on debugging while you’re doing development on a site. http://codex.wordpress.org/Debugging_in_WordPress. That way you’ll get hints as to why a page crashes and goes blank.
Second, ACF4 compatible code.
<?php $mf_post = get_field('manufacturer'); // changed variable name
if ($mf_post) {
$image = get_field('manufacturer_logo', $mf_post->ID); // changed to use object
}
?>
