@hube2 Hi man! How would I solve the same problem for an gallery field?
I use
<?PHP if(get_field('fotos')) : $images = get_field('fotos'); ?>
<img src="<?php echo $images[0][sizes][home]; ?>" alt="" />
<?PHP endif; ?>
And [08-Aug-2017 16:29:17 UTC] PHP Warning: Illegal string offset ‘home’ in