Event featured image wrapped in a link to a larger version of the same image.

functions.php

/**
 * Event featured image wrapped in a link to a larger version of the same image.
 *
 * Replaces tribe_event_featured_image to enable link to a larger version for display in a lightbox.
 * Called in custom single event template file (/pasada/tribe-events/single-event.php).
 *
 */
function pasada_tribe_event_featured_image( $post_id = null, $size = 'full', $size2 = 'large', $link = true ) {
    if ( is_null( $post_id ) ) {
        $post_id = get_the_ID();
    }
    $image_src      = wp_get_attachment_image_src( get_post_thumbnail_id( $post_id ), $size );
    $image_src2      = wp_get_attachment_image_src( get_post_thumbnail_id( $post_id ), $size2 );
    $featured_image = '';

    //if link is not specifically excluded, then include <a>
    if ( ! empty( $image_src ) && $link ) {
        $featured_image .= '<div class="tribe-events-event-image"><a href="' . $image_src2[0] . '" title="' . get_the_title( $post_id ) . '" rel="lightbox"><img src="' . $image_src[0] . '" title="' . get_the_title( $post_id ) . '" /></a></div>';
    } elseif ( ! empty( $image_src ) ) {
        $featured_image .= '<div class="tribe-events-event-image"><img src="' . $image_src[0] . '" title="' . get_the_title( $post_id ) . '" /></div>';
    }

    return apply_filters( 'pasada_tribe_event_featured_image', $featured_image, $post_id, $size, $image_src );
}