You would need to write a more specific query to identify the first published post(?) and use its ID to designate the “featured image” for the blog index header (if I am understanding your idea here correctly).

As you noted this works on page, I would also suspect your current code idea would work in single views of your posts, too.

~ Cais.

-Burt

<?php if(is_home()) {
    $img = wp_get_attachment_image_src(get_post_thumbnail_id(get_option('page_for_posts')),'full');
    $featured_image = $img[0];
}?>

It looks like it gets the ID of the page you set under “Reading Settings.” I haven’t tested yet, but looks promising. I assume I would set the condition based on is_page(‘blog’) instead of home?

For the background “Featured Image” on the Blog home page.

<?php
    if (is_home()) {
        $hero = wp_get_attachment_image_url( get_post_thumbnail_id(get_option('page_for_posts')), 'full' );
    } else {
        $hero = wp_get_attachment_image_url( get_post_thumbnail_id($post->ID), 'full' );
    }
?>

For the custom fields on the Blog home page.

<?php
    if (is_home()) {
        the_field('header_headline', get_option('page_for_posts'));
    } else {
        the_field('header_headline');
    }
?>

Could I have done this differently? Is there a standard? Thanks!