monkeybrain on "Help with the loop (custom post type taxonomy)"

Great! Now that I understand what you're trying to do, I *may* be able to help, as I'm doing something similar on one site, where I have a custom post type with a custom taxonomy, and for each taxonomy I want to list the post titles......I think you can modify this code to do what you want (I added some Idea to my code and I'll explain more below):

$terms = get_terms( 'retail_category', array('orderby' => 'name', 'order' => 'ASC') );

The first thing is to get all the terms in your custom taxonomy - in this part you would replace 'retail-category' with your custom taxonomy which is 'photo-gallery' - I'm sorting by name, which makes sense in your case too, but you can change the order by to whatever you like.

if ($terms) {
     foreach($terms as $term) {
     $args = array(
      'post_type' => 'retail',
      'posts_per_page' => -1,
      'ignore_sticky_posts' => 1,
      'orderby' => 'title',
      'order' => 'ASC',
      'tax_query' => array(
            array(
            'taxonomy' => 'retail_category',
            'field' => 'name',
            'terms' => $term->name)
      )
    );

In this section I am setting up my arguments for doing a new query (below) to find ALL (the -1) of the related custom posts fore EACH taxonomy term where the assigned taxonomy term matches (by name) the taxonomy in the FOREACH statement - my CPT is 'retail', yours is 'photos' (note: it's a better practice to name your CPTs with the singular term, not the plural, so your CPT really *should* be named 'photo' as each post is one photo, right? But honestly it's your call, you can keep it plural if you like :-) )

global $post;
    $myposts = new WP_Query($args);
      if ( $myposts->have_posts() ) {
        echo '<ul><li><h5 class="retailcatname">' . $term->name . '</h5><ul>';

Here is the query and if it finds posts within a term, then I'm echoing the name of the Taxonomy as a 'header' for the list of post titles that appear below it, you may not need to do this - and of course I'm using the UL and LI because mine is a real 'list'. If you don't want a header with the taxonomy term name, just leave out this echo and move right into the "while" part below.

while( $myposts->have_posts() ) : ($myposts->the_post());
           echo '<li><a href="<?php the_permalink() ?>">';
           echo the_title();
           echo '</a></li>';
         endwhile;

SO while I have matching posts for the taxonomy term, I list each and display it's title as a link (A). You can display whatever you want, the thumbnail and/or the content. NOTE THAT the "global $post" in the above section is required to access the post data.

echo '</ul></li></ul>';
   }
 }
}

Closing the list....not necessary if you're not using a list.

I think if you modify this to use your custom taxonomy (photo-gallery) and custom post type (photos) and then in the section with the "while" statement just echo what you want displayed, this might work for you.

Good luck!