How do I add an image field to my node.tpl.php template using render($content['field_example'])?
Ok, so here was the problem. My field_poster was nested in a Field Group under display settings. Apparently, you need to include the parent field group if you want to render child fields outside the group.

So, if my container field group is named group_fieldgroup1 I need to use the following to render my field:

&lt;?php print render($content['group_fieldgroup1']['field_poster']); ?&gt;

You can render the entire field group by using the following.

&lt;?php print render($content['group_fieldgroup1']); ?&gt;